Is RO water good enough?

maleks.reef · May 9, 2021

The title says it all. If I get an RO unit (no DI resin) will the water produced be clean enough to use in my reef tank? Thanks.

This is the product that I am considering getting: https://www.amazon.ae/gp/product/B08GSQ7YNN/ref=ox_sc_act_title_1?smid=A2PE8B2PSA99XA&psc=1

ScottR · May 9, 2021

This will probably get a lot of different responses. If your RO is good enough to keep TDS low (total dissolved solids), you can probably get away with it. But knowing what is leftover that the DI could take out but isn’t is the concern. If you have 10 TDS for example, that’s not too bad but what is it exactly. Copper, lead, other metals etc. But also, what are you planning to keep? SPS, LPS, softies, fish only? For fish only, I wouldn’t be concerned. For softies not much concern either. But for SPS, it may give you trouble down the road as the stuff that accumulates over time as you top off water may become dangerous for coral health.

fachatga · May 9, 2021

Yeah. It depends. Tds may be low but it really matters what is in that number. It may be harmless and you’re fine and it might be copper. So I’ll back up Scott. People do it though and are successful. Maybe a little luck and maybe it’s really a long term negative effect if you’re using water with small bits of bad stuff and you won’t see anything for years. Hard to say.

Bradley2448 · May 9, 2021

If your going to get an RO, just go with DI included at that point. Would save you so much headache in the long run not having to worry.

Cell · May 9, 2021

Depends. My TDS out of my RO is 3. I think plenty of reefers let their TDS creep up to 3 before changing out membranes or resin. But the cautious reefer will point out we don't know what is in that 3 and your level post RO/pre DI may be higher.