ATO ideas

OK. I was going to suggest utilizing an ATO such as mine. However, you'd need an RO/DI with an ASOV, plumbed to your tank, and room for a float valve.

You can read more about such a system on this thread, since I don't want to hijack yours.

Good luck with your solution!

 

Thanks, I do have one more question. I was looking for a pump, one not too powerful though, it's only going to be putting in a small amount of water each top off. I'm trying to decide between the Hydor Selt L20 185GPH and the Quiet One 1200 296GPH. The pump is going to be pushing against roughly a 40" head. So, which one do you think will be better? I don't want one that's going to blast the water into my tank.

 

I'd use this for a dosing pump:
Tom Aquatics Aqua-Lifter Dosing Pump

I used one for my calcium reactor... great pump. Perfect for what you want.

 

I second the aqualifter. I have a reef fanatic ATO and have it set so both float switches are in the sump. It is practically failsafe when configured this way, and is half as much $$ as the tunze.

 

RO or RO/DI units should not be hooked directly to a display tank, there are lots of disadvantages, one of which is the possibility, or really probability of a float valve failure and flooding the system with fresh water. Another is the TDS creep that results from constant starting and stopping with a float valve.
Its always suggested you fill a top off reservoir the use an ATO device from there. Reservoirs with float switches and a solenid valve are much better than float valves since TDS creep is not an issue with properly spaced switches.

 

just to expand on that, if you have the solenoid hooked to a timer, the TDS issue with a float valve is moot. Really for the same principles that make the switch superior.

 

What we mean is you want long run times on an RO membrane so it has a chance to dilute the first minute or two of high TDS water and allow itself to be flushed well with the 4:1 waste ratio.

 

Agreed.