Re: Aquatic Plants Digest V1 #67

>   CO2 injection - pH 7.3 (CO2 of about 15mg/l).  
> Your pH is high for Co2; are you using vigorous aeration or turbulence? This will
> dissipate the Co2. I think ,from what I've read recently, the optimum
> is 6.4-6.2. There are side effects on the plant's leaf chemistry at lower pHs.
> Carbonate hardness is the other factor along with pH which determines the
> concentration of Co2. See the FAQ. With your light intensity I think you 
> m ight need slightly more Co2 but reduce aeration and turbulence; your
> fish load is not high so you'll not be short of O2. If you have algae now,
> I wouldn't continue to increase fertilization because your plants aren't fully
> utilizing it, the algae is.

The pH of 7.3 is O.K. for a KH of 10. The chart says that this will translate to a CO2
concentration of about 15 mg/l. I measured PO4 and Iron today. Phosphate levels
are zero, so that can't be the cause of the algae. Iron was between 0 and 0.5 mg/l,
so I did add some more of the iron fertilizer. The Tetra Plant fertilizer explicitly
states that it contains no phosphates or nitrates.

>> Crypt. wendtii (not doing well), 
> Suspect you need to leave this for a while to establish roots and stabilize. Algae
> can also attack those slow growing leaves so keep it in check. Do NOT use algicide
> if you have algae eaters.

What it is turning into seems to be a classical case of crypto meltdown. I suspect the 
high light intensity in my tank is killing them. They did come from a low-light tank.

I don't use any activated charcoal. Now that I know that the phosphates are zero (also
the nitrate is low) I think I should maybe reduce the lighting period even further 
(now 10 hours). The algae grow mostly where the light is maximum.