[Rainer]

Two species of hygro in my low light, RCS tank are showing signs of K deficiency: small holes on lower leaves which are yellowish and dying. The tank has been dosed per EI light for low light tanks:

1/8 tsp KNO3, 1/32 KH2PO4, 1/32 K2SO4, 2x/week + Excel as directed.
1/32 CSM+B or equivalent Flourish 2x week.
No GH Booster - water is 150 ppm GH, 120 ppm KH

I've since lowered the KNO3 to 1/16 KNO3 2x/week and test results indicate sufficient nitrates. The deficiency symptoms were present but less pronounced under the higher dosage, as expected. I have both K2SO4 and an old bottle of Flourish Potassium available.

1. I'd like to use up the liquid K, then switch to additional K2SO4. How much of each should I use?
2. Could this be a phosphate or calcium deficiency instead? I've seen rapid shell disintegration in my high tech tank - whether it's because of the CO2 or a possible Ca deficiency is unclear (although the latter would point to a very high and presumably unlikely Mg-Ca ratio).

 

[Dempsey]

What kind of lights do you have on this tank?

 

[Rainer]

Stock LED bar packaged with the Tetra 10g halfmoon tank. It's sufficient to grow myriophyllum mattogrossense among others.

 

[HypnoticAquatic]

sounds like k to me, on your high tech tank it prob is a combo of high co2 and low ca but thats just from what ive read. hygro grows fast so even in a low tech tank it can use up nutrients fast from my experiance, hope it helps

 

[Rainer]

Yeah, that's the funny thing about the hygro. One species grows fast - although it seems to have slowed down lately - while the other, which is an infamously fast grower, has always been very slow in both my high and low light tanks. Test strips indicate enough nitrates in the low tech though and the myrio is growing well, so it's puzzling.

The high tech tank doesn't show any deficiencies, btw, aside from unexplained invert fatalities and rapid shell deterioration. Mystery shells are soon gone; only nerite shells are still around. Maybe it has something to do with thickness of the shell wall?

 

[HypnoticAquatic]

yea ive read that high co2 will make cabonic acid thus eating at the shell so high ca is needed to help them keep it strong once holes are present outlook norm is grim, im sure u could paint or a filler on there holes to help but never tried it, maybe try turning ur co2 down an moveing ur light up some see if it helps

 

[Sharkfood]

My tap water is has a GH of about 8-9 degrees and I still see shell deterioration in my CO2 injected tank. Allowing all the water in a container to evaporate leaves a nice, white mineral crust, so I doubt that Ca is low.

 

[JWA]

yea ive read that high co2 will make cabonic acid thus eating at the shell so high ca is needed to help them keep it strong once holes are present outlook norm is grim, im sure u could paint or a filler on there holes to help but never tried it, maybe try turning ur co2 down an moveing ur light up some see if it helps

In my non-CO2 tank I had to feed some calcium rich food for the Nerites. I also fix the shells occasionally with super glue

 

[Rainer]

My tap water is has a GH of about 8-9 degrees and I still see shell deterioration in my CO2 injected tank. Allowing all the water in a container to evaporate leaves a nice, white mineral crust, so I doubt that Ca is low.

MgSO4 would look similar, wouldn't it?

 

[HypnoticAquatic]

My tap water is has a GH of about 8-9 degrees and I still see shell deterioration in my CO2 injected tank. Allowing all the water in a container to evaporate leaves a nice, white mineral crust, so I doubt that Ca is low.

i cant tell how acidic your water is but a though i had if your water is very acidic an even ca in your water could it be possible that the acid is eating the shell away faster than it can grow? my thoughts would be yes it is plausable but i cant say thats whats going on 100% for you.

 

[Rainer]

What are the signs of P and Ca deficiencies? This is a lightly fed tank with only three embers, two snails, and RCS, so a phosphate deficiency can't be completely ruled out, unlikely though it may be.