How much Phosphates is to much?

[myreef05]

I am battling red slime. I have great water flow, feed some flake and pellets and occasionally frozen formula.
Tank is over a year old, have not had any problems til recently, upgraded my lighting 4 months ago to T-5's.
It's a 125 readings are:
s.g. 1.027
temp 80
ammonia-0
trites-0
Trates-0
phosphates 0.5 (could this cause it)?
Use only RO/DI water and it tests the same before mixing salt.
Used "chemiclean" helped for 1 week and it is back.

 

[jerthunter]

My opinion is any detectable phosphate is bad, even worse if you have low or no nitrates.
Most places I've seen recommend a level of less than .05 ppm and many test kits do not measure that low. Try using phosphate removal media and if you have macro algae try to get a noticable level of nitrates.
I know saying add nitrates sounds wierd since most people obsess over lowering it but algae uses about 16x more N compared to P. If your system is nitrate limited than red slime (cyanobacteria) tends to take over because it can use free N instead of just nitrate. If you have a Phosphate limited system you shouldn't have nearly as bad of a problem with redslime.
Sorry for rambling on, I hope this information helps.

 

[myreef05]

I do have macros, so how would I produce nitrates?

 

[jerthunter]

I've heard of people adding KNO3 to raise nitrates, apparently it is rather cheap to buy and you do not end up adding phosphates at the same time. I personally choose to just add extra food and run phosban or phoslock to keep the phosphates low.

 

[tx reef]

Phosphate levels should be around .02. If your phosphates are truly at 0, then it will inhibit growth in corals. If you are reading .05 or over, you are contributing to algae growth.
It is recommended that you drop phosphate levels slowly. A sudden drop in phosphates can be a killer for corals (actually their symbiotic algae).
I would invest in a phosphate reactor and run a mixture of ferric oxide hydroxide (rowaphos) and carbon. Start out with a small amount of media (about half of what is recommended) and gradually increase over a 1-2 week period.

 

[reefreak29]

i would suggest using phosgaurd , also since u upgraded to t5 lighting are u leaving them on the same time u had the other lights on for . im assuming u had pc before witch is a lower intence light then t5 . the cyano most likely accured with the more intence lighting since it is photosyntetic. along with the phosgaurd turn the light time down as weel , ive also noticed overfeeding can cause this . is there anyway to limit the feeding for awhile