tutorial welcomed on ro/di top off

[summer6]

I've ordered a spectrapure ro/di unit, and it should be arriving any day now...in the meantime I'm becoming confused whether I ordered the right equipment to complete the set-up.

I've spoken to a tech rep., and he's very good, but perhaps too "technical" for my newbie ears.

What I want to have is a main ro/di reservoir to gravity feed my sump with top off water, and a second container to make-up saltwater.So,I'll install two bulkheads located at the bottom of the main reservoir to accomplish this.
This is where I get unsure:
The main reservoir will have dual level controls going to a solenoid valve at the ro/di unit.
I understand that the high level float will turn "off" when the water reaches this limit.
Why do I need the low level float valve installed at the bottom of the reservoir, if the top one will shut off at max. level?
Is it only so the reservoir will never run "dry?"
Also, is it necessary to have a back-up for the solenoid valve - and would I need to install another (mechanical) float vavle above the high level float to do this?

What do people do with their sump top-off? I was planning to install a float valve there, but do I need a back-up, and what kind?

I'm not worried about the second storage container (mixing saltwater) because I can manually open the ball valve to fill it, when getting ready for water changes, but know I can install a float valve there too.
Any help is appreciated.

 

[summer6]

bump for help.

 

[swimboy123]

As far as the bulkheads and two tanks, I don't know what to tell you. What I did on my setup was to get a 10 g tank and install a float valve that my ro/di was feeding into. Then from there, a float switch is hooked up in my sump that auto pumps the water into a kalkreactor. Once the water level in the sump is maintained, it turns off the feed pump, and switches another pump on the kalkreactor to remix the effluent. On ebay, the reactor was $300 and the switch was around $75. make the reactor yourself, but that dual switch is awesome. Some of the best value I've gotten in my experiences. Hope this helps!!!

 

[summer6]

^^^Did you have a larger vessel for the ro/di water, or did it go from the unit to the 10 gal tank?
How is your total volume of 475g. in the system set-up?
Well, I also will have a dual switch for the ro/di reserve, it's mainly the sump I'm concerned about - not sure if the float valve is enough of a safety on it.
I'm not using a kalkreactor, right now the thought of adding another piece of equipment (that I don't fully understand) is not an option.lol.

 

[chrisjet]

dont need a lower level float valce why would you need one. My setup is similar to yours. I just have a float valve at the top of my resevoir and when i need water i just get it out of the spicket on resevoir. then mix sw seperatly

 

[summer6]

^^^The top float is "off," your safety.The bottom float works as an "on" switch to fill the reservoir when it becomes closer to depletion. It also helps that the ro/di unit won't need to turn on and off so many times, which helps with TDS creep. After all the reading i've done on RC, that's how i understand it.

 

[Pyrrhus]

^^^ BINGO!

I don't think that I would trust a mechanical float valve on a gravity feed from the RO reservoir. If for any reason the float failed your reservoir would dump into the sump, the RO would turn on and dutifully fill the reservoir, IE, flood your sump (and likely your floor) further until somebody noticed and corrected the issue.

A better way would be to use a backup solenoid and a high level float switch in the sump. Then, if the valve fails it will shut off the RO before it can kill the tank.

Any topoff regime that can add more than 10% of the system volume should not rely on a single point, redundancy is key.

 

[summer6]

^^^I'm starting to finally understand all the things necessary to set-up a reliable (hopefully) ro/di system.
I've decided to only go with an automatic system for filling the ro/di reserve container. That one will have the high and low floats conrolled by the solenoid, with a back-up float above them.
I think at this point, I'll just manually fill the sump, and reserve tank for mixing saltwater, with a ball valve. I may end -up using the tunzee osmolator (sp) with a small reserve tank to top-off my sump.