I bought a cheap tds
meter from ebay for like $8. i use a 5 stage bulk reef supply unit myself. Two carbon blocks, sediment filter, di
and the membrane. i added a second membrane piggybacked so I can make 150g a day. I have like 9 tanks up so I need ALOT of water. lol
I paid $180 for my deluxe unit, it has dual tds
meters so I know when to change my filters, makes it nice and easy. I start with about 130 tds
and it goes down to 0.
If you arent getting 0 tds
maybe it's time for a new DI