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Re:N and P

> So now I have had thread (not BBA) algae for the last several weeks.  Plant
> growth has been minimal and the algae has been doing pretty good (I have a
> LOT of light, 220WPC over 55g. 110@5K, 110@6,5K 12 hours/day). So,
> after a couple of weeks of pulling light green algae, this week-end I
> measured
> NO3, Fe and PO4 as a reference.
> 
> NO3 was zero, PO4 was zero, and Fe seemed (still) a little high. CO2 is at
> 2bpm in a Barr-like reactor.

You plain need more CO2. At 220 watts of PC's on a 55 you'll be using a fair
amount of CO2. This will be a big issue to get that going right. You have a
lot of light going in there.
> 
> After Tom and Steve pointed me in the right direction:
> I raised the tank about 9ppm of NO3 (Via KNO3)
> I raised the tank 15ppm (more of a guess from the tables, K2SO4 is not
> listed, KCL is. Anyone have this calculated per 1/4 tsp?)
> I added about 0.2 PO4.

I would not worry too much about K as long as it's above 10 and below 50ppm.
> 
> Here is the current result:
> Both the Algae and Plants responded. The Rotala Indica is beginning to grow
> again, everything is a little greener. The thread algae also started to grow
> a little faster and is a much deeper shade of green. Tom recommended to stay
> on top of removing it so I removed as much as I could last night, then
> measured NO3, Fe and PO4 again: 0ppm, readable, and 0ppm.
> 
> So, I added another 10ppm of NO3, and another 0.2 (and yes Steve, I
> understood what you meant by the plants will begin to slow down intake of
> PO4 once they are "full") of PO4.

I'd back off the NO3 a bit. Keep it at 5ppm or so. You got fish in there?
SAE's snails, shrimps, schooling fish etc? These will help. Adding more P
will help some.
Now that the plants AND algae are doing well...
 By removing the algae and having the plants grow eventually you will beat
the algae out when the plants get growing real well. It takes some time but
it will happen if you keep up on it, then you won't have to battle things
much once things balance out. It would happen naturally but would take a
long time. By removing it, we speed that process up. Hope this helps.
Regards, 
Tom Barr