Actually considering that Ro water has a spike in its TDS when it initially turns on, you might want to get a storage tank, so that the system does not cycle too often.

The other thing to do is have a high and low electrical float switch so the water turns on for a while and then off for a while instead of switching all day long. Then use a mechanical valve as a back-up that is placed just a little higher then the high switch.

How about?
 

How about the PH level??

Re: How about?
 

The ph level should not be affected very much by the RO water as long as you have very good aeration.

I have a small (5g) container with a small powerhead in it that I use to aerate my RO water. I fill that container 24/7 with a float valve connected to my RO. That container tops-off my sump with another float valve.

You could just get teh solenoid and float vale kit that accomplishes the same thing.

http://www.jlaquatics.com/phpstore/s..._ID=ro-kpfvkit

I have one on my RO unit and it works great. Keeps sump at constant level all the time.

I wouldn't advise that set up. to easy for it to fail and dump fresh water to the tank. what you could do is add a float valve at the end that is in the sump, and right befor that one of them pressure mechanical RO shut off's to give you double safty. this way if your selinoid sticks the float valve is still able to shut off the water through the mechanical shut off. Sorry but after working with electric selinoids for 20 years I am still leary of them on there own.

Steve

I agree, have a back-up.