over the last 2 weeks, i noticed some algae grow, my plants stoped growing,some of the plant leafe tips melting (crypto)..., then i found that my nitrate is very high, 40-50 range, the po4 more than 2, i used lemotte kits and hagen, i have 140w light on 29G, I am using EI, CO2 TANK.
I stoped adding fert, did my 50% water change, 2 days after the NO3 up again and my po4, i waited one week, did another WC and same problem again.
i have 7 red nose tetra, 5 neon, 5 black neon, 3 oto. feeding the fish one time day.
my filter is eheim 2217.
what will drive my nitrate up? po4?
the tank is 8 month old, heavy plants