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.