I have moved from buying RO, to owning and RODI (expensive filters) to making a large carbon filter
I took two RO filter containers and filled them with carbon, linked them together, and got a faucet adapter, my TDS goes from 450~ to 100~, takes about 20-30 minutes to make 30-40 gallons (depending on faucet)
I use this on my SPS grow out system, I have 0 algae issues, and always run ROWAphos anyways
I have noticed 0 difference in my corals since going from RODI to just Carbon filtered, bought a 55lb bag of carbon for $60 bout the cost of just the DI resin
oh, I use the rubbermaid trashcan on wheels, best investment for moving water EVER