How to stop water flow on RO?

I have my RO connected to my sump and want to be able to leave the water on all the time so the tank stays full (I have the floating water gauge). Only problem is the waste line would run the entire time. How can I fix this?

 

I have a 6 stage, that recycles the initial waste and recirculates it for another go, so reducing the waste water amount, but I don't think there is a 100% efficient system, I think there is always "waste water".
This is exactly what I did with my sump 2 weeks ago, its 2 weeks today since I used the 2 litre jug to top up morning and night 7 days a week !
I jet went away for the weekend, set my fish feeder, and lights onto the timer, and didn't spare a 2nd thought ! ! ! ! Ok well my mate popped in just t be safe

 

Ive heard its not the best idea to have your ro/di top off directly to the tank. its hard the filters because it would only run when the tank got low. ive heard this is hard on the filters. Maybe someone else will chime in on that.

 

Sounds like you need an ASOV or autoshutoff valve.
I agree with skurious, its not wise to plumb a RO/DI directly to a sump. It is a disaster waiting to happen when the float valve fails as in a toilet tank or evaporative cooler.

A better idea is fill a top off storage container and use that to feed your sump so it has a limited amount of treated water to flood the sump if something failed.

 

+1

You really want a container that you would fill up, not have it direct from your water line. All it takes is for that valve to get stuck open when you are away on vacation and you will end up with water all over your house and a severe drop in your salinity, which could wipe out pretty much everything in your tank.

Just get a large container- water jug, rubbermaid container, etc. and add water from your RODI every week or two depending on the size. That way if it does get stuck open its only XX gallons of total water vs. 90GPD. It severely reduces your risk...

 

I have my RO/DI plumbed to a small (probably 1/2 gallon) container with a float valve. This is then pumped into my DT using a Tom's Aqualifter pump controlled by my Reef Angel. I do need to add a water sensing shut-off valve in case the valve ever did fail. The important thing is that even if it did, it would have no effect on the water quality of the tank.

 

Thanks everyone, this was great advice. I am not going to hook it up directly.