RI/DI problem

[mike31154]

Originally Posted by Coleus

so here is what i found out

water into RO is 172, out of RO is 20 and out of DI is 4

So which one is broken?

Thx

What type of RO membranes are you running? Most 75 gpd membranes will provide a rejection rate of at least 98%. If I've done the math correctly using your numbers I get a rejection rate of 88% and you're using two membranes. My single 75 gpd membrane takes the input TDS of 210 down to 1! I'd recommend having a look at your RO membranes. If their rating is more than 75 gpd, then the rejection rate will be lower, but with two membranes you probably should do better than 88% before the DI. You mentioned in an earlier post that you replaced the restrictor? Quite often the last component changed or disturbed in any system will be a good place to start looking for problems or errors.

[Coleus]

Anyway i replied both membrane with 150GPD ones and also replace DI resin as well the flow restrictor and now it got 0ppm. However, one thing i found very interesting is that
after i replace the membrane, i got 4ppm come out and then go through a washout DI resin, i got 14 ppm. Is this normal or just weird?

[Reef-Geek]

Don't want to hijack the thread but don't feel like opening a new thread.
A question.
Do I need to add water conditioner(Prime) for the ro/di'ed water?

[Coleus]

Originally Posted by shingo43

Don't want to hijack the thread but don't feel like opening a new thread.
A question.
Do I need to add water conditioner(Prime) for the ro/di'ed water?

no you don't