Ro/di

[Gp Scott]

Looking to add to my vertex Ro/di 100 gpd with booster pump system. My inlet tds is 900 to over a 1000 soft well water with a newer membrane it gets it down to 60 now being over a year old it's 240 tds so I use a lot of di resin to get it to 0 I want to add another membrane to get tds lower before it reaches di. Any suggestions ?

[Myka]

What's the TDS if you by-pass the softener? Also, are you using a pressurized tank?

[Gp Scott]

What's the TDS if you by-pass the softener? Also, are you using a pressurized tank?

It's soft water right from well I have no water softener I already have it tee off before di canister to supply Ro water to kitchen for drinking water . The kitchen Ro has 9 gallon pressure tank

[Myka]

It's soft water right from well I have no water softener I already have it tee off before di canister to supply Ro water to kitchen for drinking water . The kitchen Ro has 9 gallon pressure tank

Ok, so the aquarium water doesn't go through the pressure tank, right? You have it tee'd off before the pressure tank, not after, right? Have you had a water analysis done? It would be helpful to know exactly what is in the water.

I think the best thing you can do is run dual RO membranes, and probably extra capacity DI filters. You really want to try to get the TDS down to 20 ppm or less before it goes into the DI resin.

I'll get the BRS guys to come reply to you - they're good at this stuff. :)

[Gp Scott]

Ok, so the aquarium water doesn't go through the pressure tank, right? You have it tee'd off before the pressure tank, not after, right? Have you had a water analysis done? It would be helpful to know exactly what is in the water.

I think the best thing you can do is run dual RO membranes, and probably extra capacity DI filters. You really want to try to get the TDS down to 20 ppm or less before it goes into the DI resin.

I'll get the BRS guys to come reply to you - they're good at this stuff. :)

Yes the aquarium water dose not go to pressure tank . It goes thru the full Ro/di cycle into a 5 gallon auto top off. I did have my water tested thru cullagan water services they sent water to lab came back good . They didn't break it down as to what was in it .
The dual Ro membrane was what I was thinking too but not sure if I need dual di .im thinking the membranes should drop it enough before it gets to di.

[Myka]

Yes the aquarium water dose not go to pressure tank . It goes thru the full Ro/di cycle into a 5 gallon auto top off. I did have my water tested thru cullagan water services they sent water to lab came back good . They didn't break it down as to what was in it .
The dual Ro membrane was what I was thinking too but not sure if I need dual di .im thinking the membranes should drop it enough before it gets to di.

Could you get a hold of Culligan and get them to email you the full results? Since it's a well, there could be a number of parameters that will trouble you - CO2 is a PITA and will burn through your DI like nobody's business.

Another thing to think of is that since you have drinking water going through the same system, you're going to get TDS creep way worse than if it was just for aquarium water. TDS creep compounds the more often the RO turns on and off. With drinking water on the system, this could be happening numerous times a day. If it was me, I'd be buying spring water to drink (they deliver, I buy a month at a time) and use the RO/DI system solely for the aquarium simply because you're dealing with such high TDS. Maybe BRS has a good win/win solution. I emailed them, hopefully they will reply today. :)

[RT_BRS]

Hey folks! Chad mentioned this thread to me so I'd figure I'd hop in.

When it comes to unusually high TDS like in your situation it can be tricky. The 100GPD membranes aren't the most efficient in the terms of rejection ratio. So for example with a GE Osmonics 100 GPD 96% rejection rate membrane filtering 1000 TDS water, you'd end up with 40 TDS making it's way through the membrane at perfect conditions. In this case the 60 TDS you are seeing would be normal.

Now, when it comes to running dual membranes, we don't recommend doing so on source water that has a TDS higher than 300. The problem is that the second membrane in series is fed with the waste water from the first which has a higher concentration of TDS.

This video here explains a bit more, and starting at around the 55 second mark gives a good example of what I'm talking about:

https://youtu.be/GE0Dhp5DZv8

And this video here just gives some general tips on overall DI conservation:

https://youtu.be/x6f07WzT2Ng

Now, what would I do in this situation? I would probably swap out your membrane and matching flow restrictor with something more efficient. Our 75GPD membrane, albeit 25 GPD slower, has a 99% rejection rate. This means you could possibly expect TDS as low as 10 under perfect conditions. You'll need to purchase a 75 GPD flow restrictor as well to have that membrane perform properly.

http://www.bulkreefsupply.com/75-gpd-reverse-osmosis-membrane-dow-filmtec.html

http://www.bulkreefsupply.com/membrane-flush-valve.html