RO/DI questions- Help!

I just hooked up my 4 stage 75gpd unit purchased from BulkReefSupply. I'm kinda freaking out because I get a very small stream, almost a very fast drip. I don't have a pressure guage but my kitchen water blasts out like crazy. I read somewhere that it can take a few gallons before it gets going at it's optimal flow. Please tell me this is true! At this rate I can go to bed and if I get up in 5 hours and check it, I may have 5 gallons! Also, my waste water is very strong.....

Also, would it be possible in the future to add an additional filter by putting it on a seperate bracket? This is the RO/DI unit:
75 GPD RO/DI 4 Stage Economy System - English


Thanks, Cat

 

I think that's normal fir a 75gpd RO.
you would be surprised how much a continuous drop of water can fill in 5hrs.

 

Thanks for the piece of mind! At least I know there's not something wrong. My next expense will be the 150gpd upgrade..lol.
Cat

 

You should invest in a pressure gauge. You'd be surprised how low your pressure can be and still "blast" out of the kitchen faucet. My pressure was very low (30-50 pressure switch) and I was getting 28-48 psi at the ro unit. The water was trickling out of the unit before the di canister. Rejection rate was 77%, which is terrible, and would have used up the di resin very quickly. I've since boosted the pressure. You need at least 50psi (avg) to get any kind of rejection rate and water production.

And yes, it will get better after a few gallons. My original TDS, after the ro membrane, was about 92, and so I didn't use the di cannister right away. Tap TDS is about 400 (fluctuates a little between summer and winter). After about a week it was 74, and after 2 1/2 weeks it was 44 (although this required "overdriving" the pressure switch to 34-54). TDS was still high, but that was all I could get out of it with the 30-50 pressure switch. If you have a well with a 40-60 pressure switch and "overdrive" it by a few pounds (was told it's not safe to go more than about 3 or 4 psi by the manufacturer when I called them), you will get decent production and rejection rate, but until you get it to 60psi and above (all the time), you will not get the 96%-98% rejection rate that is stated by the membrane manufacturer.

You don't need an extra filter canister. You should get the Purtrex 1 micron prefilter and MatrikX 1 micron (actually 0.6 micron) carbon block. With those you don't need an extra filter. Those 5 micron filters that you have are not very good.

 

It's possible that your waste water ratio is too high.You can easily check it by collecting the ro/di water in a large measuring cup for a timed period and then do the same with the waste water,it should be about 4/1. If there seems to be a problem there's a thread on this site somewhere that explains how make an adjustment.

 

A 75 GPD RO membrane will produce about 6 oz of wate ra minute under optimum conditions, that is 50+ psi, 77 degree water temp and a 4:1 waste ratio.

You probably do not have 77 degree water, most of us don't but its not a big deal as colder water actually produces lower TDS anyway.

50 psi is about average and why Dow Filmtec chose that number for their ratings rather than the 60 to 65 psi some others use.

Bulk Reef uses a non adjustable flow restrictor which I hate, I wish everyone used an adjustable of capillary tube flow restrictor so you can fine tune your RO/DI for best performance and filter life. Use a measuring cup and clock or watch and time your flows from the treated and the waste lines for one minute each. You should be getting 4:1 or almost exactly 4 times as much waste as you do good or treated water. If its much more than that you are sending too much to waste causing a pressure drop at the membrane lowering both GPD and rejection rate. If its much less than 4:1 your membrane is not being flushed sufficiently and will fail prematurely from plugging or fouling as TDS solidify on the membrane fabric.

To troubleshoot a RO/DI an inline pressure gauge and a TDS meter are a must, I cannot imagine buying a RO or RO/DI without them, they should all come standard. For $145 complete you could have the CSP-DI which includes a dual inline TDS meter, inline pressure gauge, capillary tube flow restrictor, 0.5 micron absolute rated prefilter, 0.5 micron 20,000 gallon carbon block, treated and batch tested 90 GPD RO membrane and special DI resin blended specifically for reef systems. Unfortunately, often upgrading a system costs much more than the cost of the right system to begin with.

Adding a second membrane for a 150 GPD system requires at least 65 psi incoming pressure so may not be an option.

 

Any thoughts on adding an extra DI cannister off the output for additional processing ?

 

You can always add a second DI but that may not be needed if the membarne and first DI are performing as they should. The membarne should remove 90-98+% of the TDS and the DI only has to deal with a small amount so should last a long time. Many people add a second DI to prop up a poorly performing membrane when a membrane replacement is really the cheaper and better way to go. A single DI then lasts and performs well saving money on resin from then on.

The lower end system with small horizontal DI filters and also be greatly improved by removing the horizontal DI from on top and configuring it vertically next to one of the full size 10" canisters so it fills from the bottom and exits the top. This makes the resin and water come into contact with each other unlike the horizontal that channels and short circuits. You should also fill the DI cartridge or chamber tightly with no voids or air spaces so it remains packed and water must change directions to travel around the resin beads.

 

completely normal.

 

I followed ADR's suggestion about changing the horz DI chamber to vert and it works much better. I had the DI settle and it left an free space above the resin and the water flowed there and not through the resin. I have a clear DI chamber and could see the unused resin at the bottom.
I run my input pressure at 80lbs.