# Substrate and ferts



## Vase (19 Feb 2008)

Hey,

I'm going to be setting up my main tank again and I'm currently in the planning stages, buying equipment etc when I have the readies.  Its 720 litres and will be housing Discus.
Heating and filtration sorted. Water will be RO/HMA, lighting is a MH luminaire (x3 150w x2 T8 58w, need help with bulbs - please see here). Pressurised CO2 and ph computer. I wont be getting rid of the halide or ph computer.

I'll be changing 50% of water a week via two 25% water changes. At the moment I'm looking at substrate and how I'm going to fertilize the set up. I'd like black sand or fine gravel and I don't mind forking out Â£250 for Eco-complete if its going to be worth it.

I've read various things about fert dosing but I really don't know what 'system' will be best with this set up. And it does take time to get to grips with it.

If you guys could tell me what _you_ would do in this situation that would help loads.

Thanks  

Edit: Whoops, think I put this in the wrong section


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## George Farmer (19 Feb 2008)

If it were me - 

Ferts - EI or PMDD+PO4 with dry ferts

Substrate - EcoComplete, ADA Aqua Soil, Akadama, or Seachem Flourite Black Sand.  I'd like to try out the Seachem stuff sometime myself.


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## sks (19 Feb 2008)

I can't say ECO complete is worth it, but it works for me. I was about to go with ADA aqua soil but I don't have spare tank to house the fish in for the 4 or so weeks that ADA takes to settle, leaching ammonia in the process (which is why your fish should be out of the way).

Use the pH computer to monitor the pH level. You probably want to use it to control your CO2 because you think your discus is quite sensitive to pH changes in the tank water, is that correct? I'm sure there are people who run the drop checker and constant bubbles per minute control with discus without any problems.


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## Themuleous (19 Feb 2008)

If it were me and I def wanted the black look Id get EC, its a great substrate. The only down side, and this might be an issue with the discus, is that it does buffer the water a bit, i.e. raise the GH and KH, mine went to GH 7 and KH 5 even when using RO but it does stop after a while.  I'm def going to try akadama at some stage as it looks to be a great substrate and much cheaper then other complete substrates.

If you are going to be doing a 50% water change each week you might as well do EI.  Then you are pretty much guaranteed to be given the plants sufficient ferts.  In a tank that size you dont want to be doing a complete strip down due to an algae out break the cause of which was poor plant growth.

Sam


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## Vase (19 Feb 2008)

sks said:
			
		

> Use the pH computer to monitor the pH level. You probably want to use it to control your CO2 because you think your discus is quite sensitive to pH changes in the tank water, is that correct?



Kind of. I'd be happy to use it for ph monitoring and not CO2 control providing that the CO2 wouldn't cause fluctuations in the ph, especially at night. Discus aren't really that bothered what the ph is as long as its stable. I figured that by setting the computer at a ph slightly lower than what I wanted would mean it would not only ensure the right levels of CO2 but cut it off if the ph tried to go silly. I can set the hysteris on mine quite accuratly so it wouldnt need to fluctuate a lot for it to kick in.
If that makes sense. The solonoid plugs into the plug of the controller  so I could remove the solonoid plug from that and plug it into a timer instead.



			
				Themuleous said:
			
		

> If it were me and I def wanted the black look Id get EC, its a great substrate. The only down side, and this might be an issue with the discus, is that it does buffer the water a bit, i.e. raise the GH and KH, mine went to GH 7 and KH 5 even when using RO but it does stop after a while.



I really like the look of it too, its just a shame about the price. Although ebay would be cheaper than AE. To be honest even if the Gh/Kh does go up to that level, or higher it will still be better than my tap water. The last time I tested that the Gh was at least 14. My RO unit has a DI on it so no TDS for me   

I've looked at the 'clay' substrates, I do quite like them.  If I was to go the EI route would this affect my choice of substrate? Or, _should_ it affect my choice of substrate?


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## George Farmer (19 Feb 2008)

Vase said:
			
		

> If I was to go the EI route would this affect my choice of substrate? Or, _should_ it affect my choice of substrate?



EI means that the nutrients last longer in the substrate as the plants obtain many from the water column.  A nutrient-rich substrate give you more room for error if you 'underdose'.  This is why ADA followers don't need to dose much NP to the water, as Aqua Soil, Power Sand is uber-rich.

If you do go "full EI" you need to ensure you are very heavily planted with bang-on stable 30ppm CO2.   This is why some folk go for the leaner PMDD+PO4, as CO2 can be lower with less risk of algae.  Growth is more managable too, something worth considering when maintaining a 720 litre.


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## Vase (19 Feb 2008)

Thanks George. I'm pretty sure I read something about that method on here somewhere. I'll go find it and see if I understand it   

The problems I had with this tank before were circulation problems and algae. Mainly cyano. That should be sorted this time round but I dont want to risk any algae.

With the method you suggested would I still do everything else the same in regard to water changes etc? Just the method of dosing would be different and I'm guessing the ferts used also?


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## Martin (19 Feb 2008)

Sorry to butt into your thread Vase, but was just wondering , how long is eco complete good for? do the nutrients within the substrate eventually deplete over time? Likewise  ADA  Aquasoil and Akadama.


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## Vase (19 Feb 2008)

Martin said:
			
		

> Sorry to butt into your thread Vase, but was just wondering , how long is eco complete good for? do the nutrients within the substrate eventually deplete over time? Likewise  ADA  Aquasoil and Akadama.



Nah, you dip you bread mate, its all good info


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## Garuf (19 Feb 2008)

It all depends on which ADA aquasoil and what plants, I'm lead to believe its around 12 months for amazonia.
Akadama is inert I believe but is really good at storing nutrients making it rechargeable.


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## Ed Seeley (19 Feb 2008)

Some guys on APC have their Aquasoil tanks set up for years and the plant growth is amazing.  They are adding more ferts though I imagine after a year or so as the ADA range uses stronger micro nutrient ferts as time passes.

pH changes caused by CO2 don't seem to effect fish.  I have had tanks with 30ppm CO2 during the day and then no CO2 at night.  This should cause a pH shift of about 1 yet I have spawned wild Apistos, Nanochromis and various killies under these conditions.  IMHO, you'd be best to set the CO2 level by using a drop checker and then just have the solenoid kicking in to turn it off at night.  I also use pure RO water and have never had problems despite the low pH and hardness.


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## ceg4048 (19 Feb 2008)

Hi,
    I'm not sure whether I've been looking at my substrate for too long or whether it's a case of the neighbors lawn looks greener than mine but I have a combination of EcoComplete topped with  ADA Amazonia and you, know what? The black substrate has lost it's thrill.  Maybe because it tends to turn gray under certain lighting or because light colored debris tends to make it look dirty. Maybe some of the other black substrates will look "cleaner" or more crystalline. A really dramatic substrate color I'm thinking now is the clay or brown/tan like Akadama or AS Aficana or Malaya. It's all personal taste though and perhaps some find the browns garish.  

In either case get whatever substrate you think you want to pay for and look at (that's really the most important thing). If you dose the Estimative Index (EI) method it won't matter what substrate you get or for how long you have it because your plants will feed primarily from the water column. As stated, a rich soil like AS or Ecocomplete or anything on this page is always better than a non-enriched substrate like sand but if your water dosing is up to par then really it won't matter all that much. http://www.aquaessentials.co.uk/index.p ... 6c4e6e55a8

Have you thought about filtration :?:  :idea:  Big tanks need big flow, especially if you intend to use Las Vegas level mega-lighting. Does a 7000 liter per hour filter rating sound like the ideas of an extremist? Yes, Probably... 

Did I mention big tanks have a problem with flow and CO2? Think about how you want to get CO2 into the tank. Think about the capacity of the CO2 bottles you'll need.

Cheers,


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## Vase (19 Feb 2008)

So would the PMDD+PO4 method work well enough with Akadama for example? Would it be better to add some kind of substrate ferts or would they not be needed with the above method?

I like the idea of the EI method but I'm not convinced I could keep the CO2 bang on and I dont want algae.
I'm pretty sure I read somewhere that you could use Tropica's ferts along with PMDD+PO4 but I've read so much my brain seems to have fried


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## John Starkey (19 Feb 2008)

*substrates*

Hi Vase, i have been using ec for the last six months and everything i have planted just seems to grow very well i also use ei and it seems to work for me by the same token i dont dose any po4 as worcester tap water contains over 5 ppm of po4,as for the life span of ec i am lead to believe it lasts between three to four yours, for the best results i cannot express how important it is to keep up with good husbandry it can sometimes be tedious but long term the look of your setup will benefit, regards john


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## Vase (19 Feb 2008)

Hey John,

I'll be using RO/HMA mix for my Discus as my tapwater is cack. I'm guessing I'd need to add PO4 because of this.

The more I read the more confused I'm getting  :?


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## TDI-line (19 Feb 2008)

Where are you located Vase?


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## Vase (19 Feb 2008)

Kettering, Northants


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## ceg4048 (19 Feb 2008)

Vase said:
			
		

> Hey John,
> 
> I'll be using RO/HMA mix for my Discus as my tapwater is cack. I'm guessing I'd need to add PO4 because of this.
> 
> The more I read the more confused I'm getting  :?



Vase,
           As I stated before, CO2 is s big problem regardless of what dosing scheme you use. After you have experience with your tank and are familiar with your particular configuration you can start to make adjustments with the dosing. To avoid confusion it's always better to start with an EI scheme, get accustomed to the dosing and make adjustments from there.

For 720L the following is a baseline EI dosing program (this is assuming your lighting will be equal to or greater than around 350 watts T5 or Halide):

3X per week 2.5 teaspoons KNO3
3X per week 1/2 teaspoon KH2PO4
2X per week 1 teaspoon CSM+B or 50ml Tropica Plant Nutrition
1X per week 2-3 teaspoons MgSO4

50% water change per week.  If you decide to use AS you would change water more frequently. 

You also need to have as many plants as possible in the tank from the start. It doesn't matter if you like them or not. Get as many of the the cheapest, fastest growing plants possible - Hygrophilas (are particularly good), Wisteria, Echinodorus, Cabomba etc. After a few months you can start to remove what you don't like and install those that you do like but the high biomass in the beginning will help to stabilize the tank.

Initially, dose the above quantities regardless of what your water report says or what your test kits say. I would advise to not worry about what nutrient can be deleted yet because no one else has your particular combination of water or configuration or fish etc. Use this pattern as a road map from which you can deviate later if required. You may find that you need to _increase_ PO4 or that you can get away with decreasing NO3, or whatever. You'll no doubt discover that later as you become more familiar with your tank, but you must have a baseline reference from which to work.

If you check the Tutorial Forum you'll find a sticky article regarding CO2 and it's measurement.

Cheers,


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## Vase (19 Feb 2008)

Thanks Ceg thats exactly what I was after   

Could I do two water changes with that system? 25% each. If yes when would be best?

Sorry for all the questions


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## ceg4048 (19 Feb 2008)

Hi,
     Yes, sure, but it depends on how often you do them. Let's think about _why_ we are doing a water change. There is another sticky thread in the Algae forum where water changes are discussed in great detail. Water change accomplishes the following:

1. Removes and lowers the concentration of ammonia from the tank.
2. Removes detritus and organic waste (which produce ammonia) from the tank.
3. Removes algal spores from the tank.

Ammonia is closely linked to algae in a planted tank. In fact, there is empirical evidence that ammonia is a prime causal factor in the development of alga blooms.

Ammonia, organic waste and algal spores are continually being produced in the tank at all times. If we do a 50% water change we immediately reduce the content and/or concentration of these undesirable items by 50% so that dividing your changes is a mathematical exercise or a race in how quickly these products can rebuild their levels.

Organic waste is a real enemy so you decide how often and how much water you need to replace to keep the concentration of these products at bay. 

Also remember that every time you do a water change you are also removing nutrients so you'll have to re-dose after you replace the water so you need to figure out how much to re-dose. If you intend to do two 25% changes per week then I reckon it's better to do them on the days that you would have dosed the macros. That way no fractional dosing calculation is necessary, dose the full amount.  

Cheers,


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## Vase (19 Feb 2008)

I'm going to be using a 36x18x18 tank in my main tanks cabinet for my product water. Obviously this will only hold so much water. Two 'tankfuls' each week equates to about a 50% water change. Thats the main reason. The other is because Discus love water changes and I do need to maintain a certain level of hygiene for the fish without affecting the plants.



> 3X per week 2.5 teaspoons KNO3
> 3X per week 1/2 teaspoon KH2PO4
> 2X per week 1 teaspoon CSM+B or 50ml Tropica Plant Nutrition
> 1X per week 2-3 teaspoons MgSO4



Would it be best to dose the KNO3 and KH2PO4 on the same days. The CSM+B in between and then the MgSO4 on day six?
And sorry for this really stupid question but which are the macros?


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## ceg4048 (20 Feb 2008)

OK, got it. Yep, makes sense. That you understand plants love water changes as well was the gist of it. The macro nutrients NO3 and PO4 can be and should be dosed together. The MgSO4 can be done whenever you want, but if you are doing two water changes then why not just dose it at each water change or with the NO3 and PO4? Make it easy. If day 6 works for you then yeah, go for it.

The terms macro and micro nutrients derive from the concept of the relative amounts of the nutrients plants use. For example, Plants consume (and are constructed of) mostly Nitrogen, Potassium, Phosphorous and Carbon in massive quantities, perhaps in the same way we consume meat (protein) and potato (starch). These would then be the macro-nutrients (macro=large). By comparison, we consume relatively small quantities of say, zinc or vitamin B12. In the same way plants only consume very small quantities of Iron, Magnesium or Manganese. Therefore these elements are considered micro-nutrients or "Trace Elements" since they are small amounts (only a trace amount).

Hope this clarifies.

Cheers,


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## Vase (20 Feb 2008)

So would this plan work?

Mon - CSM+B
Tues - NO3, PO4
Wed - 
Thurs - NO3,  PO4, 25% WC
Fri - CSM+B
Sat - 
Sun -  NO3,  PO4, MgSO4, 25% WC

I'm not totally sure that I've got that right  :?


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## TDI-line (20 Feb 2008)

Vase said:
			
		

> I'm going to be using a 36x18x18 tank in my main tanks cabinet for my product water. Obviously this will only hold so much water. Two 'tankfuls' each week equates to about a 50% water change. Thats the main reason. The other is because Discus love water changes and I do need to maintain a certain level of hygiene for the fish without affecting the plants.
> 
> 
> 
> ...


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## ceg4048 (20 Feb 2008)

Vase said:
			
		

> So would this plan work?
> 
> Mon - CSM+B
> Tues - NO3, PO4
> ...



Yep, nothing wrong with that!  

Cheers,


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## Vase (20 Feb 2008)

> Would you then have a pump to pump all the water in to the m,ain tank then.



Yeah. I have one of the Eheim hobby pumps that will do the job. I'll be using rigid piping if I can plum it in. Making sure that the pipe that hooks over the tank doesnt go into the water. Otherwise when you turn the pump off all the water siphons back. All you need to do is fill the prep tank with water from your main tank and mark a line where the water level is. On the main tank that is. That way you'll always remove the right amount of water and always have enough in the prep tank to fill it back up again. Did that make sense?  :? 

Cheers Ceg. Think I need to do some more reading though


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## Vase (20 Feb 2008)

Another question while I think about it   

Would I need to mix any of those ferts in a seperate solution? I thought about mixing some in a jug of tank water and then whacking it in but I dont want any of it to react or cancel the other one out etc. I know I've read that kind of thing somewhere but I'm probably way off.


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## ceg4048 (20 Feb 2008)

Hi,
     I find it easier to just add the powders directly to the tank as they dissolve easily (the MgSo4 less so). Some people mix the macros together and add about a months worth of powder to 1/2 liter of water. Then, in a separate container do the same with the micros. CSM+B does not go well with PO4 so they have to be kept apart, but everything else is fair game.

Here is a sample exercise:

If you are dosing the macros 3 times a week then that would be 12 doses in a month right?

12 doses of macro powder would be:
12 X 2.5 teaspoons KNO3 = > 30 teaspoons
12 X 1/2 teaspoons KH2PO4 => 6 teaspoons

So add these 36 teaspoons of powder to 500ml of water.

If there are 12 doses per month then each dose has to be 500ml/12 => 41 ml of solution per dose (more or less). You can play with the arithmetic to give you easy ml to dose with (41.67 is weird) so that if I wanted to dose an easy number like 50ml, well 50ml X 12 => 600ml so add your 36 teaspoons to 600ml of tap water. What happens if 36 teaspoons don't dissolve properly? No problems, add another 600ml of water and dose 100ml of the new mixture each time.

You can do the same traces with the traces (CSM+B and MgSO4) 6 teaspoons of CSM and say, 12 teaspoons of MgSO4 in 800ml of water so that each dose is 100ml.

Hope this makes sense.


Cheers,


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## Vase (20 Feb 2008)

Ceg I think I want to have your babies


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## ceg4048 (20 Feb 2008)

I'll settle for some Discus babies..   

Cheers,


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## Vase (21 Feb 2008)

When they start breeding I'll keep you posted   

Is there a thread or some info anywhere that explains why we dose with MgSO4 for example? I'm pretty much up on the others but it wont hurt to recap. I cant remember MgSO4 being mentioned :?


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## Themuleous (21 Feb 2008)

Isn't Mg added in areas of soft water?  Plenty is normally supplied via water changes, but sometimes you need to add a bit more.  I run my tank around 3/4GH and I've never needed to add extra Mg.  Maybe thats what I'm doing wrong!! 

Sam


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## Vase (21 Feb 2008)

I'll be using mainly RO water and it also has a DI chamber fitted. My HMA will give some minerals etc but maybe  not enough to save me from adding it. I dont know. 

Cheers


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## ceg4048 (21 Feb 2008)

Vase said:
			
		

> When they start breeding I'll keep you posted
> 
> Is there a thread or some info anywhere that explains why we dose with MgSO4 for example? I'm pretty much up on the others but it wont hurt to recap. I cant remember MgSO4 being mentioned :?



Hi,
     Magnesium is used in plants to construct Chlorophyll. Chlorophyll itself is mostly Nitrogen (that explains why NO3 is a critical macro-nutrient) however it's fabrication requires the presence of Mg++.  The highest concentration of Mg is found in new growth so that as the buds appear Mg facilitates the chlorophyll production that will be required as the leaf matures and initiates it's share of the photosynthesis load.

Magnesium is used to activate important enzymes in the plant. For example, one of the most important enzymes in the plant is called Rubisco. Rubisco is the enzyme that enables the plant to use and manipulate CO2 during photosynthesis.

Magnesium is an important component of the actual DNA and RNA molecules.

In addition, Magnesium acts as a catalyst in many oxidation-reduction reactions inside plant tissues. It also helps to strengthen cell walls and to increase the cell membrane permeability facilitating the movement and transport of other chemicals across the cell walls.

Cheers,


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## Vase (21 Feb 2008)

I've just thought. (I know, I was shocked too!)

Should I mix  MgS04 with something else or leave it on its own and have three fert solutions. I'm thinking if I was to mix it with one of the others I'd be dosing it three times a week  :? 

Macros 3x week, trace 3x week and MgS04 1x week?

*Bangs head on desk*


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## Ed Seeley (21 Feb 2008)

Vase said:
			
		

> I've just thought. (I know, I was shocked too!)
> 
> Should I mix  MgS04 with something else or leave it on its own and have three fert solutions. I'm thinking if I was to mix it with one of the others I'd be dosing it three times a week  :?
> 
> ...



With my RO water I just reminerlaise the new water when doing water changes.  The stuff I use to remineralise is either Seachem's Equilibrium or Kent's RO Right and they are my soruces of Mg, Ca and also add a load of Potassium too!  I think you'd be fine simply dosing the Mg with your new RO water, but as you're using a HMA you may not need to as that doesn't remove minerals from the tap water.


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## ceg4048 (21 Feb 2008)

Dude, Relax,  8)  Mg is easy. Really, you can mix the monthly Mg with anything, but just for convention, since it is a trace element, just mix it with the monthly CSM+B and call it good. In fact, depending on your tap, you may not need to add it at all. The problem is that the water reports almost never tell you about the Mg quantity of your water even though it's a component of your water's General Hardness (GH). They only ever report GH in terms of Calcium Carbonate so you would really have to test for it to confirm. I shun testing at every opportunity so I just add it and call it good. The worst crime  you will be guilty of if you add more of some nutrient than necessary is that you are wasting money. On the other hand if you don't add it and you need it then you have growth and/or algae problems. I would only be cautious about adding Mg if I had an objective of keeping the tank GH very low for breeding purposes or something like that. Plants are made up of less than 1% Mg and many plants have an Mg content as low as 0.05% so a little goes a long way, too much is no big deal, but "zero" causes problems. :idea: 

Add Mg in a way that's easiest for you. I always say that this_ is _science, but it doesn't have to be rocket science.   

Cheers,


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## Vase (21 Feb 2008)

lol...I just want to get it right. I didnt want to add the wrong thing or too much of something. If the Gh gets too high with my product water I'll just reduce the amount I use, or the frequency that I dose it.


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## REDSTEVEO (19 Jun 2008)

Hi Vase,

Just been browsing through this wonderful thread as you do 8)  I notice that the last post was February. I am dying to know how your tank is getting on and more than anything whats going on with the discus? Any pictures? Any babies?

Cheers,

Steve (A big Discus fan!!!)


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## keymaker (24 Nov 2008)

*Re:*



			
				ceg4048 said:
			
		

> You also need to have as many plants as possible in the tank from the start. (...) After a few months you can start to remove what you don't like and install those that you do like but the high biomass in the beginning will help to stabilize the tank.


I always wondered, why is that so? What kind of stabilizing is needed at the beginning? What needs to be stabilized?
Isn't the point to get enough nutrients for the plants one has, and ensure that the filter is matured, do regular water changes to reset EI dosage levels, period?

The second question is whether I should get a decent ADA substrate, or a 1cm thick Dennerle plant substrate with a regular 1-2mm grain-size gravel on top (4-10cm) would work just fine for growing plants like HC, HM, Glosso, Pogostemon, Eleocharis...  Any thoughts on that?


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## ceg4048 (24 Nov 2008)

Hi,
    New tanks suffer from ammonia transients due to lack of a stable nitrifying bacterial population. Under high lighting this encourages algal blooms. A high biomass increases the ammonia absorption for one thing but high plant biomass also produces higher oxygen levels and higher carbohydrate (Dissolved Organic Carbon or DOC) levels which directly feeds and supports the growing bacterial populations. There is a symbiotic relationship between the nitrifying bacteria and the plants, especially through their roots where oxygen is pumped from the stem to the roots thereby oxygenating the sediment. The bulk of the nitrification occurs via the sediment bacterial colonies, so a high plant biomass encourages the bacteria. Many people focus on getting their filter media "cycled" but it's actually much more important to get the sediment bacteria cycled which takes months to accomplish properly. In fact, the sediment bacteria, like all other living things required Carbon, Nitrogen and Phosphorous and these are supplied by organic products released by the plants in the form of leached proteins, enzymes, sugars and so forth. Without the high biomass of plants and bacteria to consume these organic and inorganic  products of the system the water chemistry is in a much higher state of flux. The entire tank cycling process itself is a classic example of instability as we see the production and oxidation of these nitrogen species.

Cheers,


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## keymaker (27 Nov 2008)

ceg4048 said:
			
		

> ...it's actually much more important to get the sediment bacteria cycled which takes months to accomplish properly. In fact, the sediment bacteria, like all other living things required Carbon, Nitrogen and Phosphorous and these are supplied by organic products released by the plants in the form of leached proteins, enzymes, sugars and so forth.


Clive, thanks for your answer. The nutrients you listed that are required by the bacteria are in fact the same ones we dose every day to our tanks. Should't those be enough to provide for them - assuming they can use the organic products released by the fish instead of plants? My theoretical (!) goal is to try to find a solution with minimizing the plants contribution to the equation. I know it can't be done, but I wonder why.

The other issue is disturbing the substrate with large uprooting of all FG plants for example. How much would that affect the already established bacteria? Let's say I'm replanting all my HC covering 80% of the substrate and do a 90% water change afterwards. Would that set back the "sediment bacteria cycling" process much thus increasing algae threat?


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## ceg4048 (27 Nov 2008)

keymaker said:
			
		

> Clive, thanks for your answer. The nutrients you listed that are required by the bacteria are in fact the same ones we dose every day to our tanks.


It's even more profound than that. These are the same components all carbon based organisms on the planet use, including ourselves. 



			
				keymaker said:
			
		

> Should't those be enough to provide for them - assuming they can use the organic products released by the fish instead of plants? My theoretical (!) goal is to try to find a solution with minimizing the plants contribution to the equation. I know it can't be done, but I wonder why.


Well it depends on the organism and whether they can assimilate organic versus inorganic versions of a particular element. For example plants can only assimilate carbon in the form of (inorganic) CO2. Any other form must first be converted to CO2 by enzymatic action. Animals on the other hand are incapable of assimilating any form of inorganic carbon. That's why eating a potato is good but eating a charcoal briquette isn't. We convert organic carbon to  the inorganic form by exhalation of CO2 which is a byproduct of cell respiration. Actually plants cells do this as well but it's more noticeable at night when there is no CO2 uptake. Some of our friendly bacteria can uptake inorganic P in the form of PO4. The organic forms are the most appetizing though. For example if a leaf rots , not only is inorganic NH4 produced but the DNA or Chlorophyll structure disintegrates. DNA and chlorophyll are high in N. whatever remaining ATP or ADP was remaining is also immediately attacked and absorbed since it is high in P. There is constant cannibalism and predation going on in the tank at this level and it's at this level where all the work is done. Plants can also use organic forms of nutrients obviously, but it comes at a cost because the organic unit has to be broken down enzymatically. This happens more slowly and has a lower net energy contribution (because the plant has to manufacture armies of enzymes and power these reactions using ATP which also must be produced, so the yield is lower). This works OK in a low light tank because the growth rate demand is so slow. In high light injected tanks all processes become accelerated by 5X or more, so our inorganic nutrients - KNO3, KH2PO4, which require much less complicated conversions, act much quicker since they require fewer enzymes and therefore have a higher net yield.

In a way, it's folly to attempt to remove the plants' contribution from the equation. Try not to think of it that way. Instead, think about the symbiotic relationship between plant and bacteria so they are a team. The plant feeds the bacteria and the bacteria detoxify the environment. Having said that though, it is necessary to remove the excess organic products which actually have an inhibitory effect on plant growth. In natural systems the levels of these products are kept low by getting washed away or are diluted by the sheer volume of water, but in a measly 20G tank the plants and animals  produce more than the bacteria can efficiently reduce. That's why both flora and fauna appreciate water changes. The more volume change the better. So many are paranoid about nutrient buildup but the real culprit is organic waste buildup. This is what triggers stress, toxic and pathogenic effects.



			
				keymaker said:
			
		

> The other issue is disturbing the substrate with large uprooting of all FG plants for example. How much would that affect the already established bacteria? Let's say I'm replanting all my HC covering 80% of the substrate and do a 90% water change afterwards. Would that set back the "sediment bacteria cycling" process much thus increasing algae threat?


Tthe sediment bacteria, as long as they are being oxygenated by the plants don't suffer population crash just due to being disturbed. They just carry on. The effect of sediment disturbance is more about releasing ammonia, which they have not yet had the opportunity to oxidise, escaping into the water column triggering algal blooms. Bacteria are very resilient and can't be bullied. Even if you tried to stamp them out you'd have difficulty. The new tank syndrome is simply about multiplication - can the geometric increase in bacterial population density rise fast enough to handle toxic waste production. Don't forget also that removing large volumes of water (and detritus) by default removes large volumes of ammonia and algal spores as well. The bacteria are actually attached to the sediment particles, not just swimming in the water column. The vast majority of the sediment population are unperturbed by all this activity. The water column population are affected obviously and that's what often triggers cloudiness after water changes as the bacterial populations in the column re-bloom. But this is no big deal. The bulk of the work is done by the sediment and filter media population. As the plants become healthier they do a better job of oxygenating the sediment, water column and filter colonies so that the cloudiness issues ultimately goes away after a few weeks to a few months. Higher CO2, flow and dosing generates better health which then accelerates clearer water.

Cheers,


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## keymaker (28 Nov 2008)

Cheers Clive, and thank you so much! Your answer clarified many things I was wondering about for some time now.


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