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View Full Version : Need DIY design for wasting 1st 2g of RO


Edward Smith
04/01/2012, 11:33 AM
My RO setup automatically makes water once a week with a booster pump.

I'm looking for a method to waste the first couple of gallons when it starts up, as I hear this is usually high TDS water.

I have a few designs in mind, but don't want to reinvent the wheel if there is a tried and proven method for doing this.

Do you know of any?

Thanks

rwb500
04/01/2012, 06:11 PM
i could come up with a few ideas but I think you are overthinking this issue. if you are making water once a week, i'm sure you are making enough to overcome the minor issue of the first bit not being as pure. I think the problem you are trying to avoid only actually becomes a problem when someone is trying to have their RO unit come on very frequently for very short periods of time, such as when being used as an ATO.

keep in mind the water has still gone through the carbon block and the DI resin so by most standards it is pretty clean. just not perfect. but i think you will find many reefers with beautiful reefs who never discard their first couple gallons of RO.

Mikep503
04/01/2012, 10:21 PM
I have a tds meter on mine and have never noticed any difference worth making that kind of change for. A lot of guys run successfull reef tanks off tap water. If you really think that it could be an issue I would put a tds meter on it.

Edward Smith
04/02/2012, 08:57 AM
i could come up with a few ideas but I think you are overthinking this issue. if you are making water once a week, i'm sure you are making enough to overcome the minor issue of the first bit not being as pure. I think the problem you are trying to avoid only actually becomes a problem when someone is trying to have their RO unit come on very frequently for very short periods of time, such as when being used as an ATO.

keep in mind the water has still gone through the carbon block and the DI resin so by most standards it is pretty clean. just not perfect. but i think you will find many reefers with beautiful reefs who never discard their first couple gallons of RO.

I think you right, over thinking this. I'm making 50g at a time and that will easily dilute the first couple of gallons.

Thanks

HumbleLobster
04/02/2012, 10:29 AM
The majority of the DIY solutions use +12V solenoids and some kind of logic to open/shut them. Unless you are making frequent small batches of water I wouldn't bother personally.

b442adams
04/02/2012, 12:17 PM
When I first start mine up I unhook the line to the di, because the Tds jumps up to a little over 100. It usually takes less than 1 cup of to water to drop below 10 on the tds, then I hook it back up. The only reason I do this to prolong the life of the di, since I make 50 gallons a week. Is it worth the hassle? Probably not. But I do it anyway.

skunkmere
04/02/2012, 12:54 PM
if there is a DI stage, the water still goes through a DI resin so it should be super clean. I maintain a 8gpm RO without a DI and i see the high tds when it first starts up, we have a automatic divert valve that diverts the permeate to drain for a couple minutes then to the storage tank, by then its cleaner.

Edward Smith
04/02/2012, 03:08 PM
we have a automatic divert valve that diverts the permeate to drain for a couple minutes

What kind of valve is this? Is this the same one used to flush the membrane every hour or so?

skunkmere
04/02/2012, 03:16 PM
it a huge valve, not for home use. it has a stainless steel ball that it spins in a T. one side is a drain pipe the other is the tank. I wouldnt do it. do you have DI. or have you tested the ro in the storage container. i would think the first 2 gallons of 40 tds water mixed with 20g or more of 0 tds would cancel out the higher tds.

skunkmere
04/02/2012, 03:27 PM
its a 3 way valve. this one. http://www.amazon.com/Banjo-Bottom-Load-Electric-Threaded/dp/B0079JXDTA

jmowbray
04/02/2012, 05:17 PM
This is what I plan on doing if you can understand it:

http://i842.photobucket.com/albums/zz347/jmowbray/plumbing2.jpg

Basically I currently have a manual flush valve; the ball valve will be replaced with a solenoids. All the solenoids and booster pumps will be hooked up to a PC4 (so ignore the fact that it says RKL expansion socket). The orange line are the electrical connections.