Kent RO/DI setup, malfunction?

ilovetrains

New member
I picked up a Kent Maxima RO/DI 24 GPD model from the LFS and brought it home. I read through the instructions, and completed the assembly as directed. However, things are not going as I think they should.

When hooked up to normal tap it will fill a 35 gallon container in 30 minutes. The output just seems to great. Kent recomends tap pressure of 65 psi, and while I do not have a pressure guage, I thought household pressure was actually under that figure.

If I turn the tap down to a trickle, then the Kent will trickle, BUT the third container (resin DI filter) does not even fill.

The whole thing does not appear to exerting any filtration at all. I checked to make sure the RO membrane was properly seated, it is.

Is there something else I am missing here or did I get a defective unit?
 

Doug

Reefkeeping Ninja
Premium Member
Please forgive me if this question sounds silly but you don't have the waste water and filtered water outputs mixed up?
 

ilovetrains

New member
I hope not! The instructions say waste is orange (whichmakes sense, it comes out the RO membrane tube, and does not go through the DI cannister) and the clean water is blue.
 

Doug

Reefkeeping Ninja
Premium Member
That's the color of my outputs on my Kent unit also.

Does your unit have a flush kit installed?
 

AZDesertRat

In Memoriam
Sounds like the membrane is not seated all the way in the housing. TDS readings after RO only without DI will confirm this as will timing the waste ratio.
 

Rhodesholar

New member
I would be willing to bet the membrane is not seated properly.

The reason I say this is I was sure mine was, and upon further review it was not.
 

AZDesertRat

In Memoriam
Its very common for a membrane to become unseated in assembly or shipping. You cannot tell from reading instructions or from the outside. A TDS meter will tell you very quickly as will opening the housing up and reseating it then tesing flow rates and TDS readings again. A TDS meter is your best friend when using a RO or RO/DI system, without it you are in the dark and very possibly doing more harm than good.
 

ilovetrains

New member
The direction stated it should be 1/2 inch inside the lip of the tube. It was about 1/4 inch, so I tapped it with a rubber mallet, and it went in almost 3/4 inch.

Could it have gone too far?
 

AZDesertRat

In Memoriam
TDS meters are available from any RO vendor or on ebay for anywhere from $15 to $50. They measure the total dissolved solids or electraical conductivity of the water. The idea being a properly set up RO membrane should remove about 96 to 98% of the incoming TDS and an RO/DI should remove everything. Typical tap water TDS in the US is around 250 so a decent RO unit shouldeasily get that down to about 5 or 6 and the DI polishes that off to 0. If you membrane is not seated or is defective you can easily tell it by measuring the incoming TDS and the product or RO TDS. If its much higher than 5% of the incoming then something is not right. You can also time your product and waste flows. You should waste 4:1, or for every 1 gallon of good you waste or flush 4 gallons. If the membrane is defective or not seated your product or good flows will be equal to or higher than the waste which is also an indication things aren't right.
 

old95er

Premium Member
I had the same problem when I set my Kent system up. If the membrane is not seated properly, then the product water will come out at a very high rate.

You should not be able to make 30 gallons in 30 minutes with that unit.
 

Doug

Reefkeeping Ninja
Premium Member
<a href=showthread.php?s=&postid=9826515#post9826515 target=_blank>Originally posted</a> by ilovetrains
The direction stated it should be 1/2 inch inside the lip of the tube. It was about 1/4 inch, so I tapped it with a rubber mallet, and it went in almost 3/4 inch.

Could it have gone too far?

I'm not sure how you could have gotten the membrane farther into the lip. When I replaced mine about a week ago, it only goes so far and I would think it would crack the tube that holds the membrane or damage the membrane itself.:confused:
 

AZDesertRat

In Memoriam
Under the best of conditions you should be getting 1 gallon per hour. That's at 77 degrees water temperature and 65 psi pressure. Most of us are not that lucky so flows can easily be 25 or 30% less than stated output. If you know your pressure and temperature Buckeye Field Supply has a really cool very accurate calculator on their Sponsors Forum that will tell you what you can expect from any size membrane.

Be very careful pushing membranes into the housings, they are easily damaged by compressing them and delaminating the layers.
 

ilovetrains

New member
The unit was defective. I took it back to the store, and they had the same problem. They tried another, and same problem. They replaced it with another manufacturer (coral life.) The new one works fine.
 

AZDesertRat

In Memoriam
Thats a big step down. Coralife doesn't have many good reviews. Much lower quality. I would get my money back and order a good unit from one of the RC sponsors for about the same money but a 75 GPD capacity and much better quality both construction wise and water quality wise.
 
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