What TDS # to change RO/DI membranes?

Thanks for the in-depth reply AZ, I knew you would find my thread!

To answer a few of your questions: I have the 90gpd ProPlus model. My in-line TDS meters are both reading at 0 in & out. My handheld meter is the HM TDS-3, I actually bought it off of your advice and love it. I swore it was reading a 0.01, but I may be wrong, will have to check again. I did not trim the flow restrictor as my ratio was just about at 4 to 1 so was good.

So ultimately I should get a new prefilter, carbon block & DI Resin, right? Since it's past the 6 month mark it's very possible it's not the plumbing affecting the psi since he's been done for a bit. I need to find my instruction manual to look over it for replacing those filters.

AZ, could you possibly list the exact things I should be purchasing for my 90gpd ProPlus model?

 

Pop your prefilter out for a couple minutes and taht will tell you right away if its a plugged prefilter or lower incoming pressure. If you are hooked to a self tapping valve you may want to run the needle in and out a time or two to clear any obstructions too. If its a faucet adapter take a look at the screens in the faucet.

For replacements I believe yours came standard with the 1 micron prefilter and 1 micron carbon block. If it were me, for the extra $9 I would opt for the 0.5 micron prefilter and the 0.5 micron carbon block which brings your unit up comparable with the CSP-DI they are offering now. Better protection of the RO membrane for longer life plus better carbon life too.

The DI is the SilicaBuster which is also on sale in a prefilled cartridge.
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The TDS-3 meter has what appears to be a decimal point but it is really an indicator the meter is turned on not a decimal point, they don't read down that low, only whole numbers. Same with the dual inline TDS meter, only the COM-100 has a decimal point and its only in tenths not hundreths.

If you cannot find the instruction manual all of their manuals can be found online as well as dozens of different plumbing arrangements and ways to hook up ATO's, drinking water and icemaker kits etc.
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Do you mean the membrane or the or the other filters?

 

You ROCK AZ, as always K+, will def spend the extra for the 0.5 micron & carbon if I do need them. I will take the prefilter out tonight to determine if it truly is a pressure thing. And thanks for the info on the HM handheld, makes sense.

Thanks again everyone!