my ro/di unit is only 3 months old and is water general mfg. company, everything tested good 3 months ago but phosphates didn't use ro water when i set this tank up in july, but for three months been using ro/di water 5 stage system, also seachem reef complete(calcium, strontium, magnesium), seachem reef carbonate, and only 1/3 dose of purple up, been using phos reactor for 2 weeks now with seachem phosguard. Don't have a tds check, one of powerhead shot craps want to buy a couple of new hydor koralia powerheads but sold out at dr.foster and smith, so water circulation could be an issue since hair algae going nut in last week. I'm going to stick with 20 gallons water change a month for now with phos reactor on might change to different phos remover to put in like phosban instead of aluminum oxide(seachem phosguard). Can i feed fish only twice a week i got gold stripe maroon clown, dragon goby, cleaner wrasse, sixline wrasse, lawnmower blenny, sailfin tang, yellow tang, flame angel, one mated pair of sailfin mollies, and pink spotted goby. Most just eat algae off rocks anyway.