i used to use seachem prime , and it is great . but for my discus i have now gone up to the next level and ordered a 3 stage HMA filter. kind of like an ro unit in appearence , it is essentially a 3 stage filtration system which has a 1 micron prefilter , and cartridges which remove chlorine,chloramines,dissolved metals and organic compounds. it will do 70,000 litres of water before i need to change the cartridges .
a replacement cartridge set cos £42
a 500ml bottle of prime treats 5000 litres and costs £10.29
so 70,000 divides by 5000 equals 14
thats £144.06
the hma cost £91 and comes with a complete cartridge set , so i have instantly saved £53
then each set of cartridges i buy saves me £100 in dechlorinator