Technical question/could it be done? for diy-ers!

Hey all!
I've always toyed around with the idea of auto water changers, but the other day I took it one step further. In this hobby we all go through a ton of water during water changes. We take 10% out every two weeks, dump it out (wastefully) and add 10% back. Why can't we reuse that water (the fresh portion of it) and just add new salt. Here's what I was thinking; take your "old" aquarium water and collect it in a reservoir. Then use a high pressure pump to pump it through an ro unit and take everything out of it-salt, fish waste, chemicals, etc. Then remix the recycled water with new salt and add it in during the next water change. The possible set backs here that I could think possibly come up with were the ro membrane being "clogged up" earlier with the larger salt particles in high numbers or some trace waste products not being taken out at all. Other than these possibilities, I couldn't think of anymore. I'm looking for insight and suggestions here! Has anyone else ever thought of this? There's no reason it can't be done, desalination of sea water into drinking water occurs all the time in sea locked nations. Anyway, please provide suggestions, experiences, or any technical advice you're willing to offer. Thanks and happy reefing!

 

I don't think it wud be worth the cost/effort....plop a tds meter in ur salt water its aff the charts lol you would go threw ro membranes with every wc....if u wanted to do it that way it would probably be more cost effective to boil the old water collect the steam then use that water threw a ro system ....how ever this wud still b crazy expensive just to avoid wasting water...if you have a fowler tank just leave ur wc water in buckets till the next change with a pump or air stone ...fish waste should bacterially filter out only downside would be lacking trace elements hence only for fowlr tanks. But again for the cost of water just use fresh rodi water nd mix up fresh batch.uve invested to much in your tank to skimp on the small stuff like water

 

If you look at the TDS number of saltwater, you're going to clog the membrane and run out of DI resin 100 times faster. Totally not worth it, at all.

Consider the energy it takes to run the pump, build a membrane and make the resin; that's going to be more environmentally harmful than dumping the 10g of water, which is likely about how much saltwater you could "clean" before you have to change the resin and membrane.