D9Vin

So I have had my 75 gallon with mineralized topsoil going for about two months, and despite a bit of adversity, it is running fairly well now. EXCEPT my limnophila aromatica is starting to look pretty sorry. I topped it maybe 2-3 weeks ago and the rooted portions have two new stems where they were trimmed which look pretty good, if a little light green, however the replanted tops have turned yellow in the leaves. The top is a very light green, and the older leaves have many small holes. My ludwigia palustris also has started growing some wavy leaves, and it as well as my ludwigia repens and bacopa have lost some leaves at the bottom (although that could be because they are shading themselves pretty well now). I am also having some diatom issues, and I just today noticed some green spot algae.

Here are the stats:

Co2: 3bps
Light: 140 watts (32 new t8, 108 OLD t5 tubes)

Ammonia: 0
Nitrite: 0
Nitrate: ~5-10
Phosphate: ~0-.25
Ph: >8

Inhabitants
9 pseudomugil gertrudae
5 celestial pearl danio
2 beckford pencilfish
4 cpo crawdads
Couple of other randoms

I got some fertilizers, but I didn't really want to fertilize this tank too much...

D9Vin

And now comes the thread algae, and maybe some beard algae...

D9Vin

Well, just did a massive water change, and my plants started pearling, so I am thinking maybe it is a calcium/magnesium shortage, as I have very hard water. I am also thinking maybe I am talking to myself here, via Internet, haha.

Michael

If you have very hard water, calcium and magnesium should be plentiful. Or do you mean the fresh hard water replenished these nutrients?

This is just a guess, but I wonder if the CO2 is driving the plants to grow very quickly, and the soil substrate cannot provide enough nutrients to keep up. Depending on the ingredients used, MTS can vary a lot in fertility. If the CEC is high (as we would expect from a soil substrate), the soil should be able to absorb calcium and magnesium from the water changes and hold them for the plants. Maybe a series of water changes is needed to recharge the soil with these nutrients?

D9Vin

Yeah, I was kinda thinking that the fresh hard water replenished. I am planning on keeping the water pretty fresh in there, so we will see. I am also wondering if maybe these two plants haven't rooted into the mts enough yet.

AaronT

It's a potassium deficiency. Start dosing potassium and things will turn around for the better. I mention this in the article. The potash from the initial setup runs out eventually and needs to be dosed via the water column.

Michael

Aaron, thanks for the definitive answer.

D9Vin

Is it common for it to run out so quickly? It hasn't been set up for three months yet. I dont think I have had that much growth...