Low (not non) CO2 possible? Dosing help?

[rchady]

So in reading about going the non-CO2 route, it made me wonder if you wanted just a little more growth, would LOW (but stable) CO2 work as well? For example, I have a 10G tank hooked up to pressurized CO2, but am using the little ladder setup from the Nutrafin CO2 system to deliver the CO2 to the tank. I only have 20W light over the tank so I have the rate of CO2 at a super low rate -- 1 bubble every 10s or so.

If it is possible, how would I go about dosing for this tank? I have all the dry fertilizers from back when I used to do high tech tanks, but I seem to have forgotten anything about dosing and I'm really not even sure of the target levels anymore for the various nutrients.

I would love to build a liquid dose for this, but even dry amounts would suffice. Any and all help appreciated on this.

--Robert

[Biollante]

Hi Robert,

I run a number of elevated, but not all that elevated CO₂ tanks.

Stability seems to be important.

Though I suspect it has more to do with selecting the plants than anything else.

I suspect you are getting very little elevation in CO_2(aq) using the ladder. Hanging a bowl or cup upside down and running the CO_2(gas) into it would be far more effective.

The plants and lighting dictate dosing, generally lower CO₂ tanks are lower light, therefore they require lower dosing levels. Dosing on the high side is in my ever-humble-potted-plant-opinion a good idea.

Depending on the lights, 20 watts may not be all that low.

With a small tank, it is usually best to make up a solution.

Tell us about your tank, plants, critters, and such, along with the fertz you have and others and I will be happy to advise you.

Biollante

[rchady]

Funny, I watched this thread for a while, but had no responses so I stopped logging in, expecting I'd get an email when a post was sent... I thought wrong! So, I ended up forging ahead on my own and so far it seems like things are mostly doing well.

I actually believe that ladder is working fairly well, just watching the size of the bubbles. By the time they get to the top, they are barely the size of pinheads, and in many cases are completely absorbed before reaching the top. I've found that with increasing the bubble count I can also make the plants pearl if I want.

Early on I was dosing KNO3, KH2PO4, and some Equilibrium. Initially the NO3 levels were getting sucked up pretty fast, but then they slowed way down to the point that I had to stop dosing it. So, the details of this particular tank are:

10G w/ 2x 10W (old) CFL bulbs
Fluorite substrate
Ludwigia repens x arcuata
Echinodorus tenellus
Staurogyne repens 'Tropica'
Cyperus Helferi
Blyxa japonica - never did much
some old crypts I don't remember the name of that you can't kill if you try
An apogneton bulb, think it is ulvaceus or something like that -- took over the entire tank so it was moved to a 30g tank.
Najas roraima -- has basically done nothing at all
Lilaeopsis mauritiana
I initially had some phyllanthus fluitans (red root floater), but it eventually melted in to nothingness
I initially had some Hygroryza aristata, but eventually all leaves died and I finally pulled it out -- otherwise I loved this
Some ancient java fern that is slowly recovering

I also recently added some frogbit and that is doing awesome.

The main issue I have right now is that some BBA is showing up in areas and seems to be slowly spreading, little tufts at a time. I removed a bunch of leaves the other day that had it on it, but it is also on some rocks. Not sure how to get rid of it really at this point. I believe this is partly caused by unstable CO2 levels? If so, that is very possible due to some water circulation issues I should be addressing today.

Otherwise, most of the plants are doing quite well, with the exceptions noted above. The crypts have exploded with leaves reaching the surface now. The ludwigia has to be trimmed every couple weeks as it grows like mad. The micro sword and lilaeopsis try to take over the tank if I let it.

The denizens of this tank currently consist of 6 celestial pearl danios (started as 6, now up to 12 due to some eggs not getting eaten), 1 really old male guppy (I finally tossed a female in for him), 2 hillstream loaches, 4 otocinclus, and initially about 10 regular cherry shrimp... which has now grown to probably 50+ of them.

All in all, doing fairly well, other than the BBA. Just recently I noticed the cyperus helferi is not turning as dark green as it was. It is more of a light green with a yellowish tinge, but it is still growing. I checked the NO3 levels the other day with a test kit and they came in at 20ppm, been dosing K, so not sure what else it wants. I also noted that some of the frogbit leaves also seemed to be yellowing some, or in some cases showing holes in them. Not sure what is up with that either at this point.

--Robert

[Biollante]

Hi Robert,

Off the top, I’ll try a bit more later.

That is a lot going on in a small tank.

The first thing I would consider is replacing the bulbs, I am not sure but part of what you are describing may be little more than the bulbs losing their oomph.

Probably dosing especially micronutrients as well.

Stable CO₂ is more important than the amount to most plants and I think you have already seen those.

In a small mature tank as you describe the BBA is probably an indication of the need for a good cleaning. The fact that the plants seem to have stopped needing the NO₃ you dose is another indicator that they are probably getting it from decaying plant (microbes as well) material.

More later…

Biollante

[Biollante]

Hi Robert,

I still suspect you really are not getting much of a boost CO₂ wise with the ladder, I think your description of plant performance pretty well confirms that.

Without seeing photos, it is hard to say how plant growth may be affecting light and CO₂ competition, the fact is plants essentially jettison or consume/move nutrients from leaves not receiving enough light. This can add considerable to the organic load on a tank and seriously, mess with water quality, BBA tends to be a leading indicator.

The fact you say the Nitrates you were dosing are no longer being taken up indicates the plants are taking the Nitrates from organic sources, which while easier for them is bad for the critters and ultimately the plants themselves.

My obvious question is of course; how do you know what you think you know?



After making sure everything is cleaned up, I would again, without photos and based on your description dose this tank at 2 or 3 times the normal EI rate for a 10-gallon tank.

Biollante