RO/DI Filters Question

Hey everyone, I've had my RO/DI now for about 3-4 month and have produced about 500 gallons. I know the instruction for the RO/DI unit says th filters need to be change every 2500 gallons. Not sure if this is right or not. Is there a way to test the water to get an indication if the filters should be changed?

If you get yourself a TDS (Total dissolved solids) meter, you can test how pure the water is that you are producing. I got mine from Bulk Reef Supply here:
It has a tee that you splice on your water input before the RO/DI and another tee that your splice in after the unit. You can move the switch back and forth to read your TDS before and after the filtering, I have made probably about 500 gallons with mine too, and it still reads Zero TDS after filtering, I believe once that value starts to rise its time to change filters.
Just to throw in another opinion, though I do not have one, I've become a big fan of ro/di systems with two inline tds meters. One tds goes before the ro, the other goes after. The use of two lets you know exactly where the problem is. The addition of the third external tds allows you to know when to replace the di resin.

Use your current ro/di until it needs to be replaced. In my experience, when that ro membrane goes, you are better off looking at a new unit due to filter, di resin, and ro membrane costs total. When that happens, buy a ro/di what as two inline tds...

bulk reef supply is a great place to get a custom one built.
+1 antony4688

I got my RO/DI system from BRS and I must say it's really nice, works perfect, the TDS meter is great. And I think is better to buy your own RO/DI system than buying RO water from your LFS that sometimes could not be really what they say it is.