Refillable DI unit

[Oarfish 1]

Hi, this is my first time using DI filter (the refillable type), usually just buy "life" water from NTUC.

So, I unpack the resin, put into the cartridge, put back the foam, cover it, put it back in the container, then connect it with the tap. I was adviced to let it run to wash away "dust" in the resin. I have let it run for about 20 minutes, then measure with tds, the result is 48. My tap water is 68, "life" water is 0.  What could go wrong? 

I tried to keep running the tap longer, until I fill the whole bath tub, but reading only get a bit lower: 42. 

Did I do something wrong or do I need to let it run longer? It is a single compartment DI unit (big size). 

[frostice 1]

You should actually go back to the seller and check with him. 

Anyway, it is likely due to the flow rate and yours might be too fast for the maximum contact between water and resin. 

How big is your di unit? If it's those industrial kind, you can actually plug your pump to the filter and cycle the water in your bathtub. 

[Oarfish 1]

Hi, thanks for replying. I actually bought it from another reefer (new, resin is still sealed). It is the industrial kind. 

Yeah, I was thinking about the flow rate n maximum contact too, I run it quite slow actually, it took about 2.5 hours to fill the bath tub.  Got quite confused now on what to do, did I set up the catridge wrongly...? 

[reefaquaria 17]

If you connect directly from tap, assist the flow rate to about 1-2 drops per second. This is to allow longer contact between water and resin. It takes me 24hrs to get 40L water with 0 tds.

Alternatively you can fill up a bucket with tap water and run a pump circulating the water through the di unit repeatedly until you get 0 tds.


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[yschua 4]

25 minutes ago, Oarfish said:

Hi, thanks for replying. I actually bought it from another reefer (new, resin is still sealed). It is the industrial kind. 

Yeah, I was thinking about the flow rate n maximum contact too, I run it quite slow actually, it took about 2.5 hours to fill the bath tub.  Got quite confused now on what to do, did I set up the catridge wrongly...? 

Is the direction correct? Else I think it might still be too fast flow. Just use the circulating method as it will full utilise the resin. 

[yschua 4]

6 minutes ago, reefaquaria said:

If you connect directly from tap, assist the flow rate to about 1-2 drops per second. This is to allow longer contact between water and resin. It takes me 24hrs to get 40L water with 0 tds.

Alternatively you can fill up a bucket with tap water and run a pump circulating the water through the di unit repeatedly until you get 0 tds.


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His is the industrial kind so 1 to 2 drops are too slow. 

[reefaquaria 17]

The resin is the same only different is the volume. The bigger the volume, the longer the water stay in contact with resin. So ya the rate can be slightly faster.


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[Oarfish 1]

Ok, thanks for all the input. Yes direction is correct, I followed the in out sign. Will try with slower rate tomorrow, if not working will try circulation method. 

[Oarfish 1]

Hi, last night I thought of another possibility: "in" water is leaking out and mixing with "out" water, and turn out that is what is causing the high reading. I remember there is one white rubber ring that I can't really figure out where it should be attached, and today I put it on top of the canister (yesterday I put inside the cover of resin canister). So after I try it again, reading now is down to 2. Glad I can change water today . Thank you for all the input and helping me to figure out, guys... sorry for the silly girl mistake....