RO/DI - How fast should water flow through it?

[jrodrig692]

Question- Is it better to run the water through the filter at a trickle or a moderate stream. About what rate should my product water be coming out. Thanks.

 

[monkeyboy]

RO/DI's should be run at full pressure. They are pressurized and have a restrictor which puts the perfect flow through it.

It sounds like you may be talking about the Tap Water Purifier (TWP), if so then i think its a half cup or a cup per minute but i forget...

 

[jrodrig692]

I have an older Spectrapure three stage RO, added a Kent Silicamax in another canister, and then run it through a Tap water Purifer. Have a really bad silica problem, so I was wondering if it is better to run the water slow across the membrane and filters or fast.

 

[THillson]

Run the RO unit at full pressure. If I remember right they are most efficient at 60 to 70 pounds of pressure. The pressure is what forces the water molecule through the membrane. Water temp also influences efficiency, but that was not your question. The effluent rate will dictate how fast the water runs through the DI portion of the loop. If you are worried that it is passing through the DI canister to quickly you could have the effluent from the RO unit go into one tank. Then use a valved down powerhead to run it through the DI canister into a second holding tank.

Maybe you should get a larger resin cartridge and fill it with bulk resin. I couldn't tell you offhand where to get one but I know they make them. I've seen them up to 4' tall. This would increase the contact time and should reduce the silica. One of the LFS sells water just run through DI chambers, he has one of the 4' canisters. Here's a link to his site. Seahorse Aquarium Supply

[ October 10, 2001: Message edited by: THillson ]

 

[Anonymous]

If you have a drinking water kit, you will have a 3-5 gallon tank in between the RO and DI stages. When you open the DI effluent valve to get RO/DI water, you get a VERY high rate of flow (~1gal/minute) through the DI column until the tank is empty.

I think he may be talking about this situation. I've been throttling that valve to get 1gal/5 minutes because I worry about channeling the DI resin (water takes the path of least resistance and can basically burn a hole in the resin).

 

[AquaFxIrene]

I totally agree with THillson. Contact time is essential when running water thru DI . Don't change the feed pressure to the RO, the higher the better. We have bulk DI resin available if your looking for it.

www.aquariumwaterfilters.com

 

[Yam]

I have an aquafx 4 stage model. If I turn the valve to maximum, the pressure exceeds the pressure gauge included with it. At about 1/4 open, pressure already exceeds 60psi (max reading of gauge). Should I still crank it all the way up? I run it at 45psi and estimate ~80gpd (1.5hr/5gal jug) on a 100gpd model using warm water. I thought I read that damage to the membrane may occur if the pressure is too high.

regards,
danny