i thought i wouldnt need a water change just using simple green an 0ppm nitrates

[dmk164]

on my 75 gal planted tank my bio load is small 4 angels and 6 baby rams a cpl corys and a cpl more algae eaters dont know ther name and two timy bristle nose plecos. anyway i was always at 0 ppm nitrates so i didnt think i had to do a water change to much i even seen Corys video when he showed the last tour of his shop because he was moving locations and he said the big bins in the middle that he never changed the water. well i ended up with that cyn dont know the real spelling but blue green algae but i watched another of his videos and learned to fix it with erthromyacin . to make a long story short id like to know how i got it. was it fish waist built up? also another question about simple green and iron it has .13 iron and your not supposed to go over 5 does that mean if i dose twice a week id be overloaded with iron? or does the plants eat it up? thankyou everybody.

 

[Koi]

I can't speak to the reason why cyanobacteria occurs but I usually attribute it to some sort of imbalance of your nutrients. Sounds like you have a high plant load so I don't think its from doubling your dose of easy green since you're nitrates aren't even raising. Your plants could be starving from being limited by nitrate and the algae is using the nutrients that aren't being absorbed(this is more of a guess for me). Low flow in the tank could be the culprit. Excess food, waste or decaying leaves could be settling in stagnant areas. I see people have success with erythromycin so if you go route be sure to remove as much by hand as possible. I like using this method reduces organics

 

[dmk164]

its been a week since i added the erthromyacin i got 90 percent out in water change and i did my 25% water change last night so its beautiful now