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looking to buy a RO/DI unit..questions

redfishbluefish

redfishbluefish

Officer Emeritus
Officer Emeritus
I’m not familiar with a 24gpd filter, but I’d look at the ejection efficiency. When I purchased mine, the 75 gpd membrane was the most efficient….98% ejection.

Also realize that you’ll want a DI unit as well.

I wouldn’t skimp here…..For the few extra bucks, I’d look at a 75 gpd membraine with a DI unit.

Even though you have a relatively small tank, a 24 gpd is slow. That 24 number is under “ideal” conditions. It takes me a little over two hours to make five gallons of water.
 
Classklown90

Classklown90

So many options lol okay well I will pass on the one i posted and I will sort through all the suggestions and let you guys know what I decide on. Thanks everyone
 
thirty5

thirty5

Went with BRS 5 stage. Penny wise and dollar foolish is not the best way to go IMO. You want a decent unit that will not cost as much to run. You may spend less now, but if you need to burn through more resin for example.

I am not sure of your storage capability. But I make 30 gallons at a time. You have to know how the RO unit works sometimes. When you first start the RO unit you will see the output of membrane with a high TDS value. For example when I first turn mine on, i am up well over 100, and slowly it starts to drop. It is then the DI's job to get rid of the rest of the TDS down to 0. If i leave the unit running the TDS out of the membrane drops to about 6-7, so that puts a lot less strain on my DI resin.

I originally was using the RO unit to actually act as my top-off, and I could not understand why I was burning through the resin so fast. Since I have changed to making 30 gallons at a time, my resin has lasted much much longer.

IMO you need a TDS meter, and an auto shut off. Now the auto shut off is not just a float, it is an actually piece on the RO Unit. What it does is detects backpressure and then it turns off the supply at the RO unit. If you plan on putting a float then you need the auto shut off.

http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/reverses-osmosis-deionization-systems/standard-ro-di-systems/75-gpd-ro-di-5-stage-plus-system.html
 
falconut

falconut

NJRC Member
thirty5 said:
Went with BRS 5 stage. Penny wise and dollar foolish is not the best way to go IMO. You want a decent unit that will not cost as much to run. You may spend less now, but if you need to burn through more resin for example.

I am not sure of your storage capability. But I make 30 gallons at a time. You have to know how the RO unit works sometimes. When you first start the RO unit you will see the output of membrane with a high TDS value. For example when I first turn mine on, i am up well over 100, and slowly it starts to drop. It is then the DI's job to get rid of the rest of the TDS down to 0. If i leave the unit running the TDS out of the membrane drops to about 6-7, so that puts a lot less strain on my DI resin.

I originally was using the RO unit to actually act as my top-off, and I could not understand why I was burning through the resin so fast. Since I have changed to making 30 gallons at a time, my resin has lasted much much longer.

IMO you need a TDS meter, and an auto shut off. Now the auto shut off is not just a float, it is an actually piece on the RO Unit. What it does is detects backpressure and then it turns off the supply at the RO unit. If you plan on putting a float then you need the auto shut off.

http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/reverses-osmosis-deionization-systems/standard-ro-di-systems/75-gpd-ro-di-5-stage-plus-system.html
Click to expand...

Something doesn't sound right. My RO/DI unit is used for an auto top off and to fill a storage container. My TDS reading will go up slightly when it's off, but it immediately goes down when it starts up. I have it before and after the filter. My DI also lasts for a few months and it's the smaller container. I don't think the TDS should be getting past the membrane. Maybe it's not sealed right. I don't believe that normal.
 
thirty5

thirty5

falconut said:
Something doesn't sound right. My RO/DI unit is used for an auto top off and to fill a storage container. My TDS reading will go up slightly when it's off, but it immediately goes down when it starts up. I have it before and after the filter. My DI also lasts for a few months and it's the smaller container. I don't think the TDS should be getting past the membrane. Maybe it's not sealed right. I don't believe that normal.
Click to expand...

Of course TDS gets past the membrane that is what the DI is for. If it did not get past it then why have the DI. It is very normal, that is why the dual TDS meters are before and after the DI, so that you know what is going into your DI and then out.

Next time you turn your RO on immediately check the TDS meter before the DI and then watch the number, yes it starts high and then drops. Mine starts at over 100 and then drops down to about 7, but it takes some time.

Now if you were to use just your RO unit for top off, meaning there is no fresh water reservoir, then when your RO kicks on from the float (which is pretty sensitive) it is going to push that high TDS water through your resin. You will have 0 tds into your tank, but with those short spurts from the unit going on and off then you are shooting high TDS into your DI, instead of a nice long stream to get your TDS down to let the membrane settle down. I have a 75 gallon with about 80 or so gallons in my sump so about 150-160 total water volume. I do 30 gal water changes and have ATO, can't tell you how much i burn with ATO, but I do not have to change my resin as close to as fast as I did when I was using the RO as the actual ATO.
 
downbeach

downbeach

The most significant factor in determining what RO/DI unit to get is the quality of your raw water, i.e. if your utilities uses chlorine or chloramines as a disinfectant. Or, if you use well water, etc. I've have the basic 75 gph 4 stage unit for 2 1/2 years. Considering WC's, TO's and my routine maintenance, I make a little over 110 gal. per month. In that time, it has worked out that I change the sediment filter every two months, the carbon block every 6 months and the DI resin once a year, I have yet to replace the membrane. Over time, I did add the dual in-line TDS meter, flush kit and pressure gauge to the unit to help me determine when to replace the cartridges/resin. Since we are on the same water system, I think the unit I suggested would be fine. But, put the TDS meter, pressure gauge and flush kit on your wish list.

http://www.amwater.com/files/NJ_0327001_TWQ.pdf
 
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