auto topoff, reservoir really needed?

[Treg]

Hi Randy.

My question is mainly this, is it true that every time a RO/DI unit turns on the first bit of "clean" water is actually "dirty"?

I've always had my RO/DI and ATO running straight to the sump... Am I adding dirty water to my tank every day when the unit turns on to top off my sump?
Is it really any advantage to use a large reservoir and make a couple weeks worth of top off water at one time?

 

[Randy Holmes-Farley]

Many people use RO/DI systems in an on/off mode as you suggest. I do not think the product water is dirty in the sense that you need to worry about it, but it can deplete the DI resins faster because each time the pressure is turned off and water is not flowing, ions are slowly diffusing across the RO membrane. I'm not sure of the magnitude of the effect, and if you like the way the system works for you, I'd probably stick with it.

 

[Treg]

Thanks Randy.

I do like my setup very much. I'm pretty anal about replacing filters and even use dual DI's. I just wanted to make sure that I am not defeating the purpose by daily dosing dirty water in my ATO.

 

[Randy Holmes-Farley]

You're welcome.

I think the setup sounds fine.

Happy Reefing.

 

[BeanAnimal]

I will add my .02 here.

Your wasting a LOT of water compared to a setup that uses a resevoir. Every few minutes your RO/DI unit cycles on and off, then the ASOV takes a few minutes to shut they system down. You likely use 30:1 or worse compared to 4:1 for a system that operates normally.

From my understanding this shorten filter life as well (others may be able to substantiate this, I am not prepared to and am repeating what i have read).

Lastly, I don't like the idea of having a direct endless supply of water hooked to my tank. My resevoir is a 5 gallon bucket that is in turn connected to my tank. For my tank to "flood" I would have to have a failure of 2 FLOAT VALVES, 2 FLOAT SWITCHES AND THE SOLENOID. It's just not going to happen. My worst case scenario due to a single point or 2 point failure is an extra 5 gallons of RO/DI added to the system, which it will handle without a flood, power outage sump overlfow, or significant impact on salinty.

Bean

 

[Treg]

Hey Bean.

A lot of this isnt likely with my personal setup. But I do know what you mean.
(except for the every few minutes... Your evaporation rate is so high that your ATO turns on that rapidly?)

I use the Spectrapure Automatic Liquid Level Controller. The water level needs to drop 1" before the solenoid opens. At most, my ATO runs once every 18 hrs. In the event of a power outage it auto shuts. In almost 2 years of using this I have not had it fail once. For redundancy's the Single Tank Liquid Replenisher includes a float valve to close the feed line incase of switch failure and I have also added an Aquatronica float switch so that my ACT controller can power off the solenoid. At most I will add less than 2 gallons before the second switch deactivates the solenoid.

 

[dandydan]

Hi,
My twin tds is connected after the RO and after the DI
when shut down for a few hours on start up the RO TDS can count over 100 ppm and very gradually goes down to at the moment 3, the DI unit takes care of it all but I think it may deplete quicker, so I tend to fill a few barrels and backflush on start up.
I think sometimes we go a bit overboard.

 

[BeanAnimal]

Sounds like you have thought aout your setup fairly well. The main control device for my top-off is a float valve, it pretty much drips nonstop. I lose about 5 gpd in the winter and 3 in the summer. Many single float setups cylce on every few minutes to drip an anouce or so into the tank. Your setup takes at least an inch to cycle. I wish I only lost an inch in 18 hrs

Bean