reverse osmosis and ato questions thanks!

[Johnb123]

i hooked my r/o unit to a float valve and solenoid timer (on 3 times a day) on my tank however does this method exhaust my membrane and di resin more than if i were to fill up a side bucket of water less frequently then use a another ato to fill up my tank from the bucket?

as well does the brand of R/O units really matter? it's just the cartridges and membranes that they use are different but the housings are more less the same right? could i just buy any brand same gph membrane and fit it in or do the sizes of membranes differ for different brands?

thanks!

[outssider]

the way you're doing it, you will get what's called tds creep. If you check, you will see that the first minute or so out of your ro is very high in tds so if you run it on and off constantly you will burn through di very quickly. for example: my tds out of my tap is about 250, when I start my ro/di up my tds after ro runs up to about 180 then starts to decline. I tee this off so it doesn't go through my di. After about a minute the tds after ro drops to about 10 or so then I close the tee and the water goes through the di.

pretty much all units use the same type cartridges, they are for all intense purposes the same. So the housings are the same.

[Johnb123]

Originally Posted by outssider

the way you're doing it, you will get what's called tds creep. If you check, you will see that the first minute or so out of your ro is very high in tds so if you run it on and off constantly you will burn through di very quickly. for example: my tds out of my tap is about 250, when I start my ro/di up my tds after ro runs up to about 180 then starts to decline. I tee this off so it doesn't go through my di. After about a minute the tds after ro drops to about 10 or so then I close the tee and the water goes through the di.

pretty much all units use the same type cartridges, they are for all intense purposes the same. So the housings are the same.

Thanks for the great tip Outsider i'll definitely be doing that for now on! do i also flush the membrane before and after use along with this technique or how often do you flush your membrane?

also how come i called into a lfs today to buy a membrane and they told me their same gph spectrapure membrane won't fit into my aquasafe canada membrane housing?

[Dolfan]

Originally Posted by outssider

the way you're doing it, you will get what's called tds creep. If you check, you will see that the first minute or so out of your ro is very high in tds so if you run it on and off constantly you will burn through di very quickly. for example: my tds out of my tap is about 250, when I start my ro/di up my tds after ro runs up to about 180 then starts to decline. I tee this off so it doesn't go through my di. After about a minute the tds after ro drops to about 10 or so then I close the tee and the water goes through the di.

pretty much all units use the same type cartridges, they are for all intense purposes the same. So the housings are the same.

This is interesting information. I have a similar setup, my RO is feed to my sump where it is on a solenoid valve the turns on once a day for 15 minutes for top off.

While I don't really want to burn through DI too fast I have finally got this working well and it is great peace of mind that the tank level is pretty constant. I'm more worried about the water quality though that is going into the tank? I guess I would need to take some TDS readings at my sump output as it turns on turn learn more!

[skeeter_ca]

IMHO, a RO/DI unit should never be plumbed directly to a sump. There are several reasons for this.

1: TDS creep. When the RO membrane sits with water in it with no flow the water and contaminates tends to seep through the membrane to try and equalize with the cleaner water on the other side. You end up with high TDS on both side of the membrane. When the water valve opens the high TDS flushes right into the DI resin. This will cause the DI resin to be exhausted a lot faster.

Ideally you should have a dual TDS meter (they are pretty cheap)with a probe before the DI resin and a probe after the DI resin with a Tee-valve between the 1st probe and the DI resin. You turn on the TDS meter and open the Tee-valve to the drain. Watch the TDS drop till you it gets to around 5-10(you decide what threshold you want to switch it at). Now switch the Tee to the DI resin and make some super clean water. At this time I usually switch the TDS meter over to the 2nd probe to monitor the out going water. I always make sure it is "0". I it start to read any number other than zero then my DI resin is Exhausted and I need to replace it.

B: The other reason to not hook the RO/DI unit directly to the Sump is "What if's".
What if the float valve sticks open or leaks? What if the solenoid valve sticks open or leaks? What if you use both(for that extra peace of mind) and both of these things happen? If you use both, usually one will go bad and it is not noticed perhaps for a long time because the other is stopping the water but then it goes bad and disaster.

Use a separate holding tank and turn it on when it gets low and turn it off when it is filled. Use a float valve in the reservoir to shut off the RO/DI unit so you don't over flow it and make a mess. Believe me, you will forget sooner or later to turn it off.

skeeter

[skeeter_ca]

I know these extra reservoirs, TDS meters, Auto shut off float valves add extra cost but they are well worth avoiding a major tank crash and/or flooding your house.

skeeter

[skeeter_ca]

Also just another note:

It may seem great to have a 30-55gal reservoir for your topoff water but actually that should not be done either. You use your RO/Di reservoir to fill a smaller ATO tank that has a pump in it to top off your sump when it gets low. Make the ATO container big enough to last 7-14 days but small enough that if the pump does remain on for some reason it's not likely to crash the tank with too much freshwater.

skeeter