# CO2 Balancing Act Driving Me Mad



## aaron.c (10 Feb 2016)

Hi Guys

I know the theory, but putting it into practice is driving me doolally.

My CO2 comes on 3 hours before my lights (15:00 - lights at 6) and I don't get 1 unit PH drop, less than .5 in fact.

Not long after lights come on, the fish start showing signs of distress. Dwarf Rainbows and Harlequin Rasboras.

I have surface agitation to try and keep the fish on side, but its not working.  

I am loathed to increase surface agitation, and more and it will be breaking the surface.

My KH is about 5 and GH about 4 which I don't think is going to cause any issues.

Are there any other factors which could be adding to the distress of my fish.

My drop checkers are lime green.

Any tips or gentle nudges in the right direction.

Thanks
Aaron


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## xim (10 Feb 2016)

May be that's because you already have high CO2 from the start, dropping 1 unit from that can be dangerous.
Do you have film on water surface? It can badly block gas exchange even with good agitation.


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## aaron.c (10 Feb 2016)

I run an airstone overnight for 2 hours.  I might change this to 8 hours to try and get rid of more CO2.

Thanks for the reply Xim


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## aaron.c (11 Feb 2016)

Ph in the tank this morning is 7.7 after 8 hours of an air stone running. So that is a 1 ph unit increase from when I was objecting co2 last night. 

I took a sample of tank water out and left open to the air. The PH of that is 8.1. 

Is it reasonable to assume that 8 hours of airdrome will have degassed all of the co2.

I don't understand why the tank water sample that has been left out has such a high PH

Perhaps because I add GH booster and KH booster because both are pretty much zero in tap water 

Thanks 


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## sWozzAres (11 Feb 2016)

You might have too much CO2 for those fish. I have similiar issues with Clown Loaches, they seem alot more sensitive to CO2 that the other fish I have.

Fish distress is due to both CO2 (hypercapnia) and O2 (hypoxia). You can address both by decreasing CO2 and/or increasing O2.

You shouldn't need a lime green DC. Many tanks do well with dark green as long as you have good flow, lighting etc I can get my Clown Loaches to show distress with a dark green DC even when the other fish seem ok. Dark green still covers a large range of CO2 ppm ranging from too low for plants to too much for fish so it's not a good guide.

If you have sensitive fish then I would suggest you use them to determine CO2. First make sure that you have maximum O2 at lights on by running the airstone before the CO2 comes on, not when it goes off. O2 is maximum when the lights go out and minimum when they come on. You can also lower temperature so the water holds more O2. Maybe get an O2 test kit, although I find these hard to read.

Personally I use a venturi diffuser instead of an airstone.


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## aaron.c (11 Feb 2016)

Thanks for the reply.

I just can't get my head round round it all.

I will set the airstone to come on whenever the CO2 is off.  I do have a lot of surface agitation (not breaking the surface).

I had thought that the low alkalinity could be causing the PH pen to misread, but now that the KH is at 4 ,this shouldn't be an issue.  I have calibrated it in 7ph buffer solution and it is accurate (as far as it can be with one calibration point).

Might also try the old style Up inline diffuser, not super happy with the current one (the new version) - even with freshly cleaned ceramics, the bubbles are still pretty big I think.


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## xim (11 Feb 2016)

aaron.c said:


> Ph in the tank this morning is 7.7 after 8 hours of an air stone running. So that is a 1 ph unit increase from when I was objecting co2 last night.
> 
> I took a sample of tank water out and left open to the air. The PH of that is 8.1.
> 
> ...



Normally, CO2 is continuously produced by organisms in the tank. When you takes the water sample and place it outside the aquarium, the CO2 level will be at equilibrium with the atmosphere, i.e., lower than the in-tank level.

I think pH 8.1 @ KH 4 is about right with 1.119 PPM of CO2.

The 1 unit drop works with an assumption that the CO2 level in your tank is about 3 PPM at the start. Then when the pH drops 1 unit, the CO2 level will be 10x higher or about 30 PPM. So if it is 6 PPM at the start, then it will be 60 PPM The accuracy of your pen is very important if you are determined to get the 1 unit drop because the pH difference between 3 PPM and 6 PPM of CO2 at KH4 is just 0.3.

I mean the 1 unit drop is a rough guide. And if your fish (they're Harlequin Rasboras, which are quite CO2 tolerant) can't stand it, then there is more than enough CO2 at the moment.

If you have plant growth problem and your light is low. That might be the real cause. I had mentioned that many times in the past. Although I think I am seeing some movement in the right direction now. Before it was like breaking the law or something when someone said "not enough light" here.


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## aaron.c (11 Feb 2016)

I have just changed the lights.  I had 2 x Grobeam 600s and next to no decent growth on plants.  I think they were mounted too high and not actually strong enough.

That said I did have BBA in the tank, even when running the lights at 20% whcih was very dull.

Thanks for your very helpful input


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## aaron.c (11 Feb 2016)

Grr. So ph was 7.9 at start of injection. Fish started showing distress at 7.2. Took over 2 hours to get down to 7.0 when I turned lights on. What should I try next? Much more agitation and I will be breaking the surface.


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## aaron.c (11 Feb 2016)

Ps. If my water is 8.2 when left out of tank, am I actually aiming for ph of 7.2? Not 6.9. 


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## sWozzAres (11 Feb 2016)

Assuming you have everything setup correctly, flow, nutrients, lighting etc when your lights come on, the tank should maintain a reasonably stable pH - the CO2 being injected should be countered by both the CO2 escaping and the CO2 being used by the plants. So bps should be whatever results in a stable pH when lights are on. If you later find that the plants aren't doing well, just start CO2 injection earlier to get more in there when lights come on.

Forget about precise figures, the DC must at least be dark green, it's not anymore use than that, the -1.0pH from standing water is also a rough guide. Just find a bps that results in stable pH and timing for CO2 on to lights on and stick to it. Watch the plants and the fish and adjust accordingly. Small steps.

With a KH of 5, 30ppm CO2 is pH 6.7 - but this is calculated using the KH/pH relationship so in reality 30ppm will be lower than 6.7. Since your fish show distress at 7.2 you should increase O2 by lowering temperature, use an airstone, increase surface movement etc

With a KH of 5, ph 7.2 is only 10ppm CO2 - fish shouldn't be showing any distress at those levels so I suspect your KH or pH measurements are wrong.

What are your tank parameters - temperature, size, lighting, bps, diffusion method etc, got any pictures?


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## Jaap (12 Feb 2016)

How are the plants doing? Can we have a picture?


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## aaron.c (12 Feb 2016)

Morning All

So I checked the KH again this morning (twice).  With the Nutrafin KH test I have to add 5 drops to the water to turn from blue to yellow.  This equates to 50ppm, which I have multipled by 0.056 to get 2.8 degrees hardness.

This is obviously less than the test when I changed the water on Wednesday.

Last night when the fish were showing signs of distress (surface hugging and hiding) the drop checker (with new solution in) was green.

The specs of the tank;
Juwel Rio 125
Cristal Profi e1501
Up Inline Atomiser
Co2 Art Dual Stage Regulator
Temperature: 23-24c.
Lighting: Iquatics 4 x 28w T5 (this a new addition and Co2 issues were present before this).
Previous Lighting: 2 x Grobeam 600. 60cm above substrate.
EI Dosing 
4ml of Liquid Co2 per day.
50% water change once a week with treated tap
KH and GH booster added 

Plants are ok - they are not really thriving, and their is BBA - to be expected with all this Co2 woe I guess.


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## aaron.c (12 Feb 2016)

It's so bloody frustrating, as I have all the gear, but  not quite enough idea.  There is something I am not doing right, or some lightbulb moment yet to be had.

In other more positive news, we spotted a baby cory yesterday


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## Wisey (12 Feb 2016)

aaron.c said:


> It's so bloody frustrating, as I have all the gear, but  not quite enough idea.



I feel your pain, we are in the same boat, haha


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## ian_m (12 Feb 2016)

You will generally not get correct pH reading (both pen and test kit) when GH/KH is below 8'ish for a cheap pH pen/kit and 4'ish for a proper pH pen/test kit. This could be your issue, completely incorrect pH readings.


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## aaron.c (12 Feb 2016)

Wisey said:


> I feel your pain, we are in the same boat, haha


It's a bloody miserable boat isn't it


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## aaron.c (12 Feb 2016)

ian_m said:


> You will generally not get correct pH reading (both pen and test kit) when GH/KH is below 8'ish for a cheap pH pen/kit and 4'ish for a proper pH pen/test kit. This could be your issue, completely incorrect pH readings.



Thanks Ian - is it normal for KH to drop from 5ish to 2.8 in 2 days?

Could you reccomend a decent PH pen?

Thanks for the advice Ian


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## Wisey (12 Feb 2016)

The one I was looking at was:

http://www.hannainstruments.co.uk/p...resistant-ec-ph-and-tds-low-range-tester.html

But it is not cheap, especially once you start adding in storage solutions, buffer solutions, cleaning solutions, calibration solutions, and god knows what else. I was like, hmmm, what do I really need from all these possible solutions... If you spend a lot on a decent pen, you want to store and clean it properly, so its quite an investment.

My Aberdeen tap water is softer than butter on a summers day, 2 German degrees, so even a decent pen won't give me a reading unless I do something to my water parameters. I bought a load of oyster shell chicken grit and a filter bag to see if I can harden my water a little this way, but have not tried it yet.


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## Wisey (12 Feb 2016)

Just to add, that pen does TDS as well which can be useful if you want to keep shrimp as I understand it. You can save some money just going for a PH Pen.

http://www.hannainstruments.co.uk/ph/meters/pocket-phep4-water-resistant-ph-tester.html
http://www.hannainstruments.co.uk/ph/meters/pocket-phep5-water-resistant-ph-tester.html

Not sure what the difference is between Phep4 and Phep5, I'm about to go Google it.

Edit: The Phep5 has a greater accuracy.


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## aaron.c (12 Feb 2016)

Wow! That is expensive, I was looking at http://www.hannainstruments.co.uk/ph/pocket-phep4-water-resistant-ph-tester.html

Our tap water is less than 10ppm caco3


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## ian_m (12 Feb 2016)

aaron.c said:


> Could you reccomend a decent PH pen?


No sorry not got a pH pen, as to get a proper one is too much for any benefit I would get, as I currently get green/yellow drop checker all over my tank. I was aware, from reading instructions, that in low KH/GH regions, pH pens are not accurate.

Brief explanation why here.
http://www.ukaps.org/forum/threads/does-low-kh-cause-issues-with-plant-growth.39805/#post-432335


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## aaron.c (12 Feb 2016)

Thanks Ian. How do you factor in the delay with the drop checker? Do you just aim for green 1 after lights on or something? Thanks 


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## aaron.c (12 Feb 2016)

What one are you going to order @Wisey - I am loathed to spend that much money on a PH tester, but I think I am going to struggle without it.
The drop chckers are too slow to respond really.


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## ian_m (12 Feb 2016)

aaron.c said:


> Thanks Ian. How do you factor in the delay with the drop checker? Do you just aim for green 1 after lights on or something?


You need to aim for green drop checker, when positioned anywhere in the tank, at lights on. I turn my CO2 on 2 hours before lights on.

It should not be like this...., though fish don't seem to mind, especially if you have been aerating your tank before CO2 on.



 

Does take a lot of patience and fiddling to get it right. When starting I had CO2 issues, in that, BBA appeared on some plants whilst others were fine. Placing the drop checker, that was nicely green when at top of tank, amongst the plants the drop checker stayed blue. Adding a 3200l/hr power head, suitable positioned,  fixed that CO2 issue and my drop checker is now green where ever I place it in the tank. I have my power head on from 2pm CO2 on time until 7pm.

I have also found CO2 levels is very very dependant on spray bar angle. Spray angled down and I get a yellow drop checker, spray up (giving surface ripple) and I get a blue drop checker. Currently my drop checker is on blue side of green after spray bar fiddling this weekend. Leaving as is for the moment as I am away and tank is "turned down", 1/2 light level, 1/2 time on, 1/2 ferts etc as tank will have to run for next couple of weeks by itself.

My last 2KG FE lasted 200 days on 180l tank @ 8 hours a day. So that's 2000/200/180/8 -> 0.007gr CO2 per litre per hour I am using. See what value you are getting ?


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## Wisey (12 Feb 2016)

At the moment I don't intend to order anything as I know that none of them will work in my tap water. If I did order one though, I would get the first one that I listed, the 98129 version as it does TDS as well. I figure if I am spending a decent chunk of cash in the first place, I might as well spend a little more and get that one. At the moment though I have a rescape and a wedding in August to pay for! 

I'll see how I get on with my new regulator and running my tile at a higher intensity. Before the reg issues I didn't have a problem getting the DC to be lime green and staying lime green through the photoperiod, I just had a problem with growth. Mick from Tropica looked at pictures of my plants last year and stated it was lack of light, so now I have CO2 (although not consistent until the new reg arrives) and higher light and I am starting to see growth, I hope I can be like Ian and just observe and use the DC. Agree its annoying the delay though, if I had harder water I would have the high quality PH Pen and do the profile etc.


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## aaron.c (12 Feb 2016)

Ok guys, thanks for all the advice.  Good idea Wisey - it's probably not worth dropping a 100 quid on a PH pen and then calibration solutions.

I will try with the drop checkers.  

I will probably just raise it to limit where fish show distress, and then slowly creep it down over a couple of days, while looking for the dark green checker.


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## Wisey (12 Feb 2016)

Just make sure you move around the DC to lower levels and near plants that have higher CO2 requirements, make sure you are getting it where you need it. My noob mistake when I first setup my aquarium last year was to buy one of the ones that hooks over the top of the glass rim. Looks lovely, but turns green and stays green whatever the CO2 was as it reads so close to the surface! Buying one that went lower down and near the substrate showed that I only had a blue\green level where I really needed it.


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## dw1305 (14 Feb 2016)

Hi all,





aaron.c said:


> I don't understand why the tank water sample that has been left out has such a high PH


It is like Xim says, it is because of the CO2 ~ HCO3- equilibrium. If you have any dKH, at 400ppm atmospheric CO2, the waters pH will be ~pH8, because of HCO3- ions in equilibrium with dissolved CO2.

I don't use CO2, but I have soft water (rain water) and pH just isn't a very useful measurement in low TDS water. Conductivity (TDS) is measurable with a relatively cheap meter, but it doesn't really help with CO2 measurement.

Cheers Darrel


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