# EI Or PMDD?



## AverageWhiteBloke (20 Feb 2010)

Just embarking on mixing up some fert mix, I have been adding the kno3, phos and mag sulph dry direct to the tank with leaf zone traces purely because before buying my powders I had just bought a large bottle of Leaf Zone and wanted to use it up.
After reading various articles I'm a bit confused on whether to go down the PMDD route or use the EI method, from what I understand so far I believe EI is mainly for brightly lit heavily planted aquaria where my set up is a 165 litre sort of 50% planted with low light only 70 watts in tubes. I do dose co2 through gas as oppose to chemical although I am having trouble finding out the right quantities at the moment. :? 

I look forward to any input or a good starting base to work from which I can adjust when I need to.


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## chris1004 (21 Feb 2010)

You can use either dosing method on your tank but IMO you'll find it a lot easier to master the EI method. The 50% water change isn't set in stone but does seem to put a lot of people off. But when you get used to doing it and set yourself up with the necessary hardware it shouldn't be an issue. 

Your lighting isn't that low at all, in fact its 1.93wpg but you don't say if this is T8, T5 or T5ho flourescent tubes. If it is T5 or T5ho then this is quite high lighting in fact as they are upto 80% more efficient than T8. The abitary 2wpg is considered to be quite high lighting by most although sometimes you do here of people running upto 6wpg   . Its not quite as cut and dried as that though depth and clarity of water play an important role as does the height of the luminares above the tank but I certainly wouldn't on the face of it consider your lighting to be low.

Do you have a drop checker set up correctly i.e. with a 4kh referance solution? If you haven't then IMO you should set one up but assuming you do aim to get the DC into the light lime green colour which should give you about 30ppm which seems to be about the ideal level for both your plants and fish. Ensure you have enough flow to evenly distribute this throughout the tank and that the level remains constant throughout the lighting period and is turned on 2 hours before your lights.

It shouldn't matter to much what trace elements you use so long as they are designed for aquatic use. I'm not familiar with the one your using but if your in doubt there are usually fact sheets available where you can check the quantities of individual elemants and 'James planted tank' website has a quite usefull trace element comparison table that you could cross referance this with. Its fine to add the dosing salts directly to the tank its just that a lot of people myself included find it easier to make up a stock solution. It certainly saves a lot of faffing around with measuring spoons and tiny quantities of this and that above the water surface and delivers the ferts in a pre diluted format which has to aid even distribution throughout the water column.

Regards, Chris.


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## CeeJay (21 Feb 2010)

Hi AverageWhiteBloke.

The advice given by chris1004 is very sound indeed, so I would go with that.
FYI, I have 90w over 180 litres (our light to litre ratios are pretty similar) and I am dosing full EI.
You can always start with the full EI levels and tweak it downwards each time you mix up your monthly batch. That way you can keep an eye on your plants health, as any adjustment takes 2-3 weeks to take effect. If you get to a point where your plants are affected just go back up to the previous months levels.
This EI mularkey does get easier the more you do it, as I'm sure many on here will attest.
Good luck.


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## plantbrain (22 Feb 2010)

AverageWhiteBloke said:
			
		

> Just embarking on mixing up some fert mix, I have been adding the kno3, phos and mag sulph dry direct to the tank with leaf zone traces purely because before buying my powders I had just bought a large bottle of Leaf Zone and wanted to use it up.
> After reading various articles I'm a bit confused on whether to go down the PMDD route or use the EI method, from what I understand so far I believe EI is mainly for brightly lit heavily planted aquaria where my set up is a 165 litre sort of 50% planted with low light only 70 watts in tubes. I do dose co2 through gas as oppose to chemical although I am having trouble finding out the right quantities at the moment. :?
> 
> I look forward to any input or a good starting base to work from which I can adjust when I need to.



No, you do not need a "brightly lit" tank, I've never stated this is a requirement or for such tanks, it's(higher light) used to drive growth at a max level and thus uptake will also be assumed to be at a max level, which would represent an upper bound.

This way, it's non limiting regardless of the light intensity.

To make the system more manageable however, using less light works best.
I've made this point 1000's of times and list it anytime I reference EI and made it as easy to see/find/hear/notice as possible.

Most every tank I set up and have personally is lower light.
Discus folks have long done 50% 2x a week water changes.

This is nothing new.

You can adjust things down from non limiting high level, to suit by simply watching and slowly progressively reducing the amounts added week by week till you see plant stress.

This assumes you know what good CO2 is and looks like. CO2 is 10X more an issue than anything nutrient dosing wise.
 No one has ever killed their fish with EI or dosing KNO3 I am aware of.
On say 5-10 plant forums, we see at least one a week that gasses their fish.........

Water changes are easy and can be automated if desired, water is also a lot cheaper than test kits which cannot be automated. It's a trade off.

Less light makes demand for CO2/nutrient reduced, so you have more wiggle room with dosing/water changes.
Some user skill and observations, progressive reduction can extend water change frequencies out farther, but you cannot over do water changes for tank/plant health. 

With a simple U shaped drain and attached to shower, you can drain and refill and not do much. You can sit and type replies to forums while this is being done :idea: 

Cough cough.......

Not hard, even an old person with a bad back can do it.
Test kits over time?
Few keep using them.

Motivation to test is very low, most do not calibrate test kits either, even when they are aware they should........water change is a much simpler step.

This tank gets EI, has less light than your tank etc.






I spend maybe 30 minutes a week at most. Most of which si waiting for drain/refill, I trim and harvest weeds to sell, remove RCS to sell etc.


Regards, 
Tom Barr


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## plantbrain (22 Feb 2010)

There's also some hybridization of PMDD+PO4 and uses EI but like PMDD daily dosing and stock solutions.

You can also chose say just NO3 as the test parameter to adjust via test kits using the PMDD+PO4 methods. James has a simple good run down, I have a few versions of this on my website. 



Regards, 
Tom Barr


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## AverageWhiteBloke (24 Feb 2010)

Many thanks for all your input.   For some bizarre reason I had wrongly calculated my WPG by getting the sum the wrong way round which I didn't realise until after posting. So as you all rightly have pointed out my lighting is not as low as I first thought. The lighting is also 10000k T8's Chris to answer your question.
After my error I then checked out James PT site and thought that the PMDD-PO4 method of dosing was best suited to my situation and made up 2 stock solutions @
Macros
25g Potassium Nitrate
2.8g Potassium Phosphate (monobasic)
11g Potassium Sulphate
20g Magnesium Sulphate Heptahydrate (Epsom Salts)
500 ml distilled water

Micros
10g Chelated Trace Element Mix
250ml Water
0.5ml Normal Hydrochloric Acid

This I have been dosing daily since the weekend at 4ml of macros and 2ml of micros based on the fact my tank is currently not heavily planted as suggested by James on the site. So I guess now I need to do some calculations to work out correct doses using the stock I have already made up to go down the EI style of fertilising.
I suppose disregarding the low planting I could quite safely double up to the full dosage based on Toms advise that providing more than is required and lower lighting is a lot better option leaving less chance that the plants will never be wanting for anything.
Any suggestions for levels as my stock is at a slightly different make up than the one in the EI method?
So far most of my thinking from keeping a planted tank in the past has been turned on its head. So far through this board I have sorted my water, planting, pruning and now my lighting. The next thing is as mentioned will be correct Co2 levels. I do use a DC but mine has been giving me strange results and is not AFAIK in a 4DKH solution unless the Red Sea fluid has something in it to keep it at the right KH. Reading an article on UKAPS I now see the importance of the DC fluid and that using tank water is not the best way to go about checking levels (ordering some right after this post) hopefully the Co2 levels will be the last piece of the jigsaw. 
I always believed the likes of Toms pictured tank here would take extremely high lighting and sophisticated equipment out of my price bracket so to know that results like that can be acheived with relatively low light but correct dosing methods and water maintainance is inspiring.


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## plantbrain (25 Feb 2010)

Don't feel bad, when I first started adding KNO3 and K2SO4, they got mixed up and folks where saying to add more K+ to anything that ails thee at the time. Fortunately, this did not cause any issues for me. A few of us make lots and lots of mistakes, but once we get it right, there's many things we know we did and can rule out as possible causes. 

But..... we have to get it right.

Low light simply increases this chance we actually have a nice tank without algae and healthy, but managed growth.
Perhaps more than any one thing. Lots more wiggle room for most every aspect of planted aquariums. Here's a lower light tank, 180 cm sitting here today, needs some trimming and then grow out, some more stems and grow out in the rear etc.














Cardinals and other critters are happy, frisky, well feed, eat most anything. Sorry for the point and shoot photos, I may actually do a real photo shoot someday. This tank is admittedly a long way away from any of that. But the rate of growth is good, you can do quite a lot with low light. Light is on for about 8.5 hours, and is about 110 cm from the tops of the foreground plants. About 2w/gal at that long distance. I could easily get about 1.3-1.5W/gal of T5 lighting.

The stock solution you made was very weak on PO4. Do not worry, juicing up the PO4 will help more than many think. 
I'd double or triple that amount, I add about 4-5x that amount in the tank above for example. So I dose 2-3x a week: 15ppm of NO3, 5ppm of P04 etc, K+ is well over 20ppm and not used as much as the N , so there's always excess K+.

If light is low, good CO2/current, consistent dosing, there's a great deal of upper range to play around with. Folks generally mess up with CO2 or not adding enough. Most people figure it is better than really adding a lot more than they told you to. Like I did with KNO3 a long time ago, but it taught me that there was no adverse effect. So I was not scared about over dosing. There was no risk.

Regards, 
Tom Barr




Regards, 
Tom Barr


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## plantbrain (25 Feb 2010)

AverageWhiteBloke said:
			
		

> I always believed the likes of Toms pictured tank here would take extremely high lighting and sophisticated equipment out of my price bracket so to know that results like that can be acheived with relatively low light but correct dosing methods and water maintainance is inspiring.



Many think this, "more is better" attitude towards lighting, but "less is better" attitude towards nutrients.
Above a light compensation point(growth= respiration), low light is better for most everyone' goals.

You are correct, CO2 will be a huge challenge, it's among the most dangerous(this is the no#1 way to kill fish in a planted tank) and definitely the hardest to accurately measure and maintain. It moves it's concentration in a few minutes dramatically in some cases. Current has a large influence of CO2 also. So you have a number of things that make it a particularly vexing parameter. Many do not realize the importance, give it a passing glance.
Respect the gas...........

Lower light will make that much easier. Higher light if you want more CO2/algae issues/potential should you neglect or overlook the maintenance, but you get faster growth.

I spend all my energy learning as much as you can about how folks add CO2, what and how to do it best.
That will not be wasted effort.

Regards, 
Tom Barr


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## CeeJay (25 Feb 2010)

Hi all
Slightly off topic, but wow, what a tank.
Stunning job Tom, as always.
That just had to be said


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## AverageWhiteBloke (26 Feb 2010)

My kh4+brom came today may be a stupid question but does it matter how much is used in the dc? just bottle says add 5ml but my dc only holds about 2ml before b the level being higher than the inlet


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## chris1004 (27 Feb 2010)

Hi,

No it won't matter as long as the ratios of 4kh water- bromahide blue are the same which being the premixed version cannot change. Be aware though that some have had dodgy batches of this from AE of late so if things don't look quite right check the solution. You can do this roughly by using a KH-PH chart for your tankwater and looking at the drop checker to make sure they are roughly in the same ball park but remember that if the solution is correct then it will be more acurate.

Regards, Chris.


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## AverageWhiteBloke (27 Feb 2010)

hmmm I don't have a ph test kit at the moment, the issue I have with my solution is the colour in my dc is so faint it's hard to make out verging on clear and it is from AE. From a distance it looks like there's nothing in.


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## chris1004 (28 Feb 2010)

Hi averagewhitebloke,

Maybe worth a read through for you.

http://ukaps.org/forum/viewtopic.php?f=37&t=10019

Regards, Chris.


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## AverageWhiteBloke (1 Mar 2010)

Thanks Chris that is exactly what's happening to me, I'm sort of stuck between a rock and a hard place on this one.
 I will try another test and make sure the DC is well sealed and not mixing in tank like in your link but to be fair the fluid is a very pale colour before it even enters the tank, once in the tank this is made worse by the brightness of the lamps.

I still have a few tests worth in my Red Sea fluid, would it help if I was to add a drop of this to the AE+Bromo mix to improve the colouration making it clearer to read or would this mess with the ratio giving a false result.  Could I had a drop of any PH test kit? 

The last test I did with the AE stuff gave a very faint blue reading which was difficult to see and after changing this back to my Red Sea mixed with tank water got a nice green after a couple of hours   Thing is I can't really rely on either at the moment.

I have no reason to suspect there is a problem with the AE stuff as it does say add 5ml which I would imagine would improve the colour compared with only about 1.5ml in my DC, maybe worth giving them a ring. I notice that their glass DC comes with fluid which I obviously don't need right now.

When Tom said the Co2 is the hardest to measure he wasn't joking


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## AverageWhiteBloke (1 Mar 2010)

I've been in touch with AE today who have said that how vivid the colour is will depend on how much fluid is used which is common sense I suppose,their dc's must use 5ml which would be clearer to get a reading. As I have never had his product before and without anything to compare it too I suppose I'm stuck.
AE did say though that I can't put a drop of my Red Sea reagent in as its is orange rather than blue so I'm guessing they are two different chemicals, but I could add more bromo as the ration of 4kh to Bromo was not that important.
Not sure whether to get bromo or different DC, JBL should work as its blue.
Any suggestions


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## plantbrain (2 Mar 2010)

Well, you can estimate CO2 by elimination.

Use the DC and other cues as estimates only, and then the eyeballs and the plants for the rest.

You can also hedge your bets by using rich sediments, eg ADA As or soils etc, osmocoat, Worm castings and so on, simple dosing methods to the water column, then with nutrients covered, you simply use low light, most will let you know thwe right amount for the tank you have specifically and what brand, bulbs they like etc.


So that's nutrients and light ruled out, that leaves just CO2/current etc.

Current, just have good current and plenty of it, filtration etc some surface movement, but no breaking the water's surface.

Then estimate the CO2, and tweak SLOWLY from there and wait a week or two in between each adjustment.

Regards, 
Tom Barr


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## AverageWhiteBloke (2 Mar 2010)

Thank you again Tom, the Co2 levels are quite an important factor to me due to the type of aquarium I have which is an Aqua One AR850. This is a system type with built in wet dry filtration built into the lid, a power head picks up the water and sprays it over 2 filter baskets in the lid which then runs back via gravity into the tank, this does not cause much surface disturbance due to the inlet being below the water level but I do feel that the spraying over the media may be detrimental to CO2 levels de-gassing the column rather faster than it would with an enclosed system like canisters. Back in the day about 15 years ago when I first had a crack at planted aquaria I had a open top tank with a Mercury Vapour pendant above and canister filtration, the co2 diffuser was also attached directly to the outlet and to be fair I did have a lot more success with plants even without the new information I have picked up here plus a lot of the reading I was doing at the time has been turned on its head as more is learnt. My work commitments and the MV lighting bleaching out my wifes wallpaper   made me scrap that set up and go with this system for easiness of maintenance.

Anyway I digress, I have posted elsewhere about some plant problems where leaves are not growing on lower half's of plants with slow growth and a bit of BGA. Just through this post I now know its not my lighting which contrary to my belief may actually be TOO bright that I may need to turn it down or provide more nutrients and co2 in level, which I now know the dosing levels to aim for to go with my full lighting. That only leaves the co2 levels(should I use the full lighting) which as a UKAPS member pointed out in another post could be co2 deficiency and the BGA has also been associated with fluctuating co2.

I have changed from a weekly water change to every two week to see if the rapid change of co2 content at change time will help with the BGA. So really the only thing out of my control is the co2 content, that's why I'm trying to get at least a few stable readings out of some tests, that way I can confirm whether or not to have the full lighting on as I would like to have some plants that like higher levels of lighting especially some of the redder varieties which make a nice contrast in the tank.

With the process of elimination I'm hoping that my fears are not confirmed about my filtration system, I don't suppose I will know for about another 3 week. I have been dosing Toms recommendation of ferts for nearly two week so changes will take time to show, No3 tests show low so I'm assuming that goes for all the other nutrients in the column so have turned off one tube to give the plants less stress being forced to grow too fast without what they need. Once the no3 levels get up a bit and growth a bit better I'm hoping to kick in that other tube and change from PMDD+PO4 to EI dosing then I will be able to figure out if my co2 system can keep up with everything else or its the Achilles heal.
That being the case I suppose my options are keep lower light species and turn down the lighting, switch to a liquid carbon source or possibly do away with the filtration and switch back to canisters easily done with a bit of lid modifying (I could just use the lid space to keep my gear in)

Sorry for the long winded post just thought I'd clear up what my long term aim is rather than I'm doing a bit of whining about the colour of my DC fluid is which I appreciate is not an exact science at the best of times even if you can get a definite reading


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## chris1004 (2 Mar 2010)

Hi averagewhitebloke, (whats your real name mate we can't keep calling you that).

I do understand exactly where your coming from I was new to this planted tank hobby only a year ago and it can all seem quite daunting especially when everything you read and hear contradicts what the real experts have to say on forums like this one. i.e the Tom Barrs and Clives of this world.

Sort your drop checker out first and go from there, thats my advice. Buy a new one if you have to or whatever. I have had trouble with AE myself before and don't find them very forthcoming when things go wrong to the point where I won't buy from them anymore. But hey thats just me and this post will probably be pulled cause I'm having a dig at a sponser, hey ho. 

Regards, Chris.


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## AverageWhiteBloke (3 Mar 2010)

Thanks Chris it's Neil BTW, I have ordered a Chameleon DC from Ebay just waiting for that to come. I am getting a slightly better reading from the one I have although it is very faint, I think the problem may be that the fluid is so light that when it's just in between blueish to green that you can hardly tell, last night it was still slightly bordering on blue so I turned up the co2 and will check to see if its a more definite green tonight when I get home, I couldn't make it out this morning as its impossible to read without the tank lights on. As you recommend I'm also going to get a PH test from my local fish store today, I have already got a KH tester so I can check the integrity of the 4KH+Brom reading although I know my KH will have no reading as this is all I ever get. My water is very soft from the tap which I used to buffer up but as I can never get my co2 readings out of the blue so have stopped hoping this will help.

The BGA is starting to become a bit of a problem, I had to clip out some fine feathered plants last night that were too badly affected and wipe it off the leaves I could. It seems to be mainly along the front edge of the tank but not limited to there. Like you said contradictory advice, some people say stir up the sand to loosen it up which I did! others say do not disturb the gravel in fear of releasing ammonia into the column so could be that possibly not :? 

I've also been thinking about my dosing, at the moment going with that afore mentioned PMDD+PO4 mix, when I tested my NO3 at the weekend I was getting next to no reading. Would you suggest stepping up the dosing and if so to what? Tom has said that he would at least double if not triple my dose which I'm currently dosing double @ 8ml macros and 4ml micros.
Or maybe I should switch straight to EI method of dosing now instead of waiting to see what my current dosing will achieve. I read a lot saying that with any Algea problems more ferts is better than less.

What sort of doses would I have to administer of the mix I have to achieve same levels as EI?


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## dw1305 (3 Mar 2010)

Hi all,


> that the spraying over the media may be detrimental to CO2 levels de-gassing the column rather faster than it would with an enclosed system like canisters.


 This is correct, the trickle filter will be very efficient at de-gassing the CO2, as the large surface area of tickling water will exchange both CO2 and O2 until the level in the water is in equilibrium with the atmosphere. If you don't add CO2 this is an advantage as the CO2 won't be depleted as rapidly (whilst the plants are photosynthesising) as it would in a filter with a lesser gas exchange capacity. If you do add CO2 it will be rapidly de-gassed until it equilibriates with the atmosphere, the higher the differential between the tank water and the atmosphere the quicker the de-gassing will occur.

This is also why wet and dry trickle filters are very good for keeping fish with a high oxygen demand (like Hill stream loaches or Hypancistrus), they will retain high oxygen levels at night when all the bio-load will be respiring because of this gas exchange capacity and they have a huge biological fitration potential. This is how the old fashioned "clinker bed and revolving arm" sewage treatment plants work.

cheers Darrel


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## plantbrain (3 Mar 2010)

I seal the dry section of the wet/dry filters and reduce the spill over into the weir boxes to about 3-5cm.
I use duct tape, but some suggested gaffer's tape to seal up any air leaks in the wet/dry box section.

The goal is to prevent exchange of gas.
CO2 can still degas there, but it just gets redissolved since it cannot vent.

Good if you have a fish only tank, but bad if you want to add more CO2.

The wet/drys are still very good though.
I use them on all my tanks, but they need just a little modification is all.

Also, CO2 and O2 are independent, so adding more CO2, does not displace O2, likewise, high O2 does not displace CO2. Respiration of fish is a two way street still(CO2 and O2), so when we add CO2, we should also consider having really good O2 as well, this allows us to add more cO2 with less risk to fish health/reduce stress etc.

I use high current and high CO2 and lower light, this is the best scenario for fish and plant health.
Also makes management 10X easier.

BGA tends to be due to poor filter mainteance, flow etc, or low NO3.
Blackout (3 days search here for this) or EM antibiotics etc. with subsequent dosing and upping of KNO3.

I neglect the KNO3, I get it coming in slowly.

Algae and plants can be used in this manner to judge what needs done and "fix its".

Basic routine maintenance, some gardening is all that's left.
Much simpler, easier than all the other techy method,s test kits and what not.
Most folks have a goal of a nice planted tank with moderate growth, reduced labor and a little gardening.
So the method should reflect that with a logical step wise approach that uses methods most are familiar with and have few assumptions/skills required.

I also practice what I preach:


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## dw1305 (4 Mar 2010)

Hi all, 





> Also, CO2 and O2 are independent, so adding more CO2, does not displace O2, likewise, high O2 does not displace CO2. Respiration of fish is a two way street still(CO2 and O2), so when we add CO2, we should also consider having really good O2 as well, this allows us to add more cO2 with less risk to fish health/reduce stress etc.


 The reason for this is that high CO2 levels become a problem as the difference between the concentration in the water and the fishes gills approaches equilibrium, at equilibrium there is no differential, the CO2 doesn't diffuse into the water, and the fish asphyxiates.  The combination of high CO2 and low O2 is the combination that is likely to prove fatal. However a fish may be stressed and suffering from hypoxia long before the obvious signs of distress occur, this is why I don't add CO2, even though plant growth will be improved by CO2 levels well up into the 100's of ppm.

The same applies to O2, it is the differential between the O2 conc. in the tank water and the fishes gills that affects the rate that O2 diffuses into the fishes blood, high O2 means quicker diffusion into the blood and  gives the fish to withstand (but not necessarily enjoy) high CO2 levels.

The final factor is not all fish are equal and Anabantoid fish, for example, (Bettas, Gouramis etc.) from warm, still waters have adaptations (air gulping, the anabantoid organ etc) to allow them to survive low O2 levels, (warm water holds less O2 than cold water). Another factor is that the lower conc . of salts in the water the higher the O2 capacity (this is partially why you can stock less marines per volume of water than tropicals), and yet one more factor is atmospheric pressure, as this declines the O2 holding capacity of the water declines, meaning that if you want to keep fish from a warm water with a high oxygen demand (say Rio Xingu plecs) it is best not to live in Denver.

cheers Darrel


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## plantbrain (5 Mar 2010)

dw1305 said:
			
		

> Hi all, A However a fish may be stressed and suffering from hypoxia long before the obvious signs of distress occur, this is why I don't add CO2, even though plant growth will be improved by CO2 levels well up into the 100's of ppm.



So what metric would you propose for a sublethal sign of stress that an aquarist could see and measure?

How about breeding events and fry? I've breed discus, which are more sensitive to CO2 than other species due to lower O2 at higher temps and their larger size, larger fish in general, are more sensitive to respiration issues involving CO2. Angels and cories and plecos and tetras etc.

Speculation answers little, our systems are not particularly natural and we have complete control of CO2/O2/light/ppm's etc. Obvious signs of stress are all most aquarist have to look for, but breeding is generally a good sign that the fish are doing well, even by standards that do not include nor have anything to do with plants/CO2 enrichment.

Dose makes the poison, not the mere presence of a gas/chemical. 
Copper can kill shrimp, but at a correct dose, it's essential.
All or nothing mind sets do little good, particularly when you leave the issue unanswerable.
They are based on fear, speculation, not observable facts.

Maybe they are true.......but the statement above does not demonstrate that.
Breeding events and long life etc, good careful measurements with data logging with specific cases wherre breeding has occurred, brings skeptical questioning to such speculation.

Example:




All these angels are bred and raised in this tank, they have never seen any other aquarium. discus have breed at least a dozen times, cories etc, CO2 is at about 35ppm, light is low, about 25 micromols at the bottom, so CO2 demand is also low/easier to manage. We pushed the CO2 to about 45ppm for extended periods, more was the max the discus could tolerate without color changes.  

We used a light thermo IR method to measure CO2 in situ using a data logger. No issues with KH/pH and accuracy to +/- 1ppm. Few aquarist have such equipment. 

Such data/observations does answer the question reasonably.
You can make your own conclusion from there based on the results.



> The same applies to O2, it is the differential between the O2 conc. in the tank water and the fishes gills that affects the rate that O2 diffuses into the fishes blood, high O2 means quicker diffusion into the blood and  gives the fish to withstand (but not necessarily enjoy) high CO2 levels.



Perhaps, if they are getting it on and living and looking really healthy, eat like pigs, not shy, not sick, not signs of stress by any metric that's non destructive.........(Killing fish is not an option for most folks), I would suggest there's little basis for such statements. Show me some evidence in a practical aquarium. I've shown mine after all.

Where's this proof that it happens as you say? In planted tanks? ADA has a huge list of examples, so do most aquascaping contest, aquarium after aquarium, I look at fish differently, breeding etc.
I think those are pretty good signs things are going well, and long life. 



> The final factor is not all fish are equal and Anabantoid fish, for example, (Bettas, Gouramis etc.) from warm, still waters have adaptations (air gulping, the anabantoid organ etc) to allow them to survive low O2 levels, (warm water holds less O2 than cold water). Another factor is that the lower conc . of salts in the water the higher the O2 capacity (this is partially why you can stock less marines per volume of water than tropicals), and yet one more factor is atmospheric pressure, as this declines the O2 holding capacity of the water declines, meaning that if you want to keep fish from a warm water with a high oxygen demand (say Rio Xingu plecs) it is best not to live in Denver.


[/quote]

Very true, good points. George Booth speculated that his fish where more sensitive than my discus since he lived high altitudes. That was 12 years ago I think? I had measured 35ppm, he had measured 15ppm or so, I had 2.5X more light though. Measurement errors and assumptions could also easily explain the difference as well.

I sold 230 Blue diamonds from that batch of 5 adults.

I have plenty of Rio Xingu plecos. Among my favorite fish as a whole.
Still, I think the points about CO2 being a higher risk for fish than say what many suggest, nutrients like NO3 etc, is much better founded. When used judiciously, CO2 is not an issue to long term health, when used carelessly, it's the no # 1 killer in the plant tank hobby.

Still, that is a human management issue/problem, not the fact that we can use CO2 well and still have a long term healthy place for fish where they can breed, eat like piggies etc.

I have a non CO2 planted tank, works very well. But I am on both sides of the fence, CO2 also.
Both can be done well, there's strong evidence this is the case.

Regards, 
Tom Barr


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## chris1004 (6 Mar 2010)

Hi Tom (plantbrain),

When you refer to lower lighting levels what sort of WPG figures would you be using? 

I know the WPG rule is only a rough guide and there are also other factors in play i.e. reflectors, water depth/clarity, height above water of lights type of lights, biomass. etc etc. 

But in my instance for example my lights are 6" above the water surface with reflectors, 20" deep tank and gin clear water. At the moment I have 2WPG of T5 HO lighting and I'm seriously looking at decreasing it following your sound advice in this thread but what in lamans terms would you suggest I aim for. Are there any pointers or further practical advice that you can give me. I understand it largely depends on what plants I have aswell. Mostly I've come to really like the various crypts having tried many varieties but as I understand it Crypt Parva needs a lot of light which is what I am growing as a foreground plant.

Love your tanks by the way.

Regards, Chris.


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## AverageWhiteBloke (6 Mar 2010)

Sorry for not replying sooner I've been away working.  


> The wet/drys are still very good though. I use them on all my tanks, but they need just a little modification is all.



This has made my weekend   pure genius. My biggest fear was that this system was not fit for purpose as I bought it when I gave up planted tanks for fish only system. Water change this weekend and I have an idea involving some cling film and elastic bands. 8) Another problem sorted.



> BGA tends to be due to poor filter mainteance, flow etc, or low NO3.



I clean my two tray filters on a 15/30 pattern as one on the 15th day the other on the 30th of each month, I also do a 30% change with dechlorinated and warmed water once every two week. The flow is quite good as the weight of the water dropping through the opening in the lid circulates well most of the plants even furthest away can be seen moving in the current. As for the NO3 I'm working on that now, question is would I be better increasing NO3 on its own while keeping my current dosing schedule or increasing the amount of both macros and micros in line?

I believe the O2 should be ok, temp is 24 deg medium stock of fish and as Tom said my filter is quite effective at gassing/de-gassing the column 02/co2 respectively. Also the fact that the lid also has water in it I suppose this offers more of the surface area to the air which would also would help.


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## dw1305 (6 Mar 2010)

Hi all.
I wrote "However a fish may be stressed and suffering from hypoxia long before the obvious signs of distress occur, this is why I don't add CO2, even though plant growth will be improved by CO2 levels well up into the 100's of ppm." and Tom wrote "So what metric would you propose for a sublethal sign of stress that an aquarist could see and measure?"

I've never kept fish with added CO2, so unlike Tom (PlantBrain) I have no personal experience to offer, but there is quite a lot of literature (from the Aquaculture industry) that suggests prolonged exposure to sub-lethal CO2 levels will have long lasting effects on fish health.

The technical terms are "hypercapnia" & "nephrocalcinosis", and this is the Google Scholar search for "hypercapnia & aquaculture" <http://scholar.google.co.uk/scholar?hl=en&q=hypercapnia aquaculture&um=1&ie=UTF-8&sa=N&tab=ws>. A lot of these references concentrate on Sturgeon, Trout and Salmon (fish from clean, cool, highly oxygenated waters), rather than the much more pollution tolerant Channel Catfish, Carp or Tilapia.

The below section is abstracted from: 
"Water quality and welfare assessment on United Kingdom trout farms" 
CM MacIntyre (2008) Ph.D. Theses Aquaculture University of Stirling 
<https://dspace.stir.ac.uk/dspace/handle/1893/434>

".....Carbon dioxide is toxic to fishes because increases in ambient CO2 concentrations result in the fish being unable to excrete endogenous carbon dioxide, leading to CO2 increases in the blood, known as hypercapnia. As a result of this, the blood pH decreases, leading to acidosis, reducing the oxygen carrying capacity of the blood in a process called the Bohr effect. The reduction in blood pH weakens the bond between haemoglobin and oxygen molecules, resulting in the release of oxygen molecules which then passively diffuse into cells that have a low partial pressure of oxygen. This effect has been observed in salmonids at water concentrations of CO2 of around 20 mg/L* (Westers 2001). Danley et al.(2001) recorded reduced growth in rainbow trout over a 90 day experiment with CO2 concentrations up to 45 mg/L, but there was no report of significant mortalities at this level. Clinical signs of carbon dioxide toxicity include moribund fish, gaping mouths, flared operculae, and bright red gill lamellae (Summerfelt 2002). A well known effect of CO2 in conjunction with hard water, is nephrocalcinosis (Harrison 1979a, b, Smart 1981, Fikri et al. 2000). This chronic degenerative condition of the kidney is characterised by calcareous deposits (Harrison & Richards 1979; Smart et al. 1979). The white gritty kidney deposits consist of calcium salts, occur within the ureters on the surface of the kidneys, and the kidneys become swollen, sometimes with fluid-filled cysts (Harrison 1979a). The kidney is a major haemopoeitic organ in fish, and blood haematocrit values and haemoglobin content decrease in affected fish (Yurkowski et al. 1985). Severely affected fish become dark in colour, have a swollen abdomen and most of the functional kidney tissue is destroyed (Harrison 1979a; Yurkowski et al. 1985).  Nephrocalcinosis occurs when natural CO2 levels in the water are high and/or when additional oxygenation is used to increase carrying capacity, and the total amount of metabolic CO2 excreted is increased as a result (Harrison 1979b). CO2 levels of 12mg/L induce nephrocalcinosis, with higher concentrations increasing the prevalence and severity of the condition (Harrison 1979b, Smart et al. 1979). Although CO2 level is a primary factor in the induction of the condition........"

*mg/L. is equivalent to ppm (H2O has a density of 1g/ml, and there are a 1000g in a litre, and a 1000mg in a gram and therefore 1,000,000 mg/L.)


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