Poly Bio Marine makes the Kold Steril units, they are nice because there is no waste water and if you want water in a hurry all you do is turn it on. The down side is if you have any phosphates, silicates in your water you will need the alumina media and you will need to run the water through slower. The alumina media does not last that long if you have high
PO4 and Silicates. I have a KS and
RO/
DI and I switched my reef over to KS and ran with that water for about 6 months and I did not change out the alumina media when i should have and I got cyno real bad. I also noticed my corals were not growing much. Which
PO4 can effect coral growth. So I switched back to
ro/
di and got a phosban reactor for the cyno issue and what a difference.
IMO there is no better water then
ro/
di, if your going to run a
fowlr that a KS would be great, I use the KS on my
fowlr with no issues.
Check your water before you buy the
ro/
di unit and if you have
PO4 or Nitrates get the duel
DI unit. I run a duel
DI on my unit and it has helped out with my
PO4 issue. A
TDS meter is a good investment, do not go by color change alone and buying non color change resin is cheaper at most places.