Question about RO/DI

cope413 · Jan 21, 2015

I recently discovered my inline TDS meter was miscalibrated and my DI has probably been spent for 3-6 months.

My tap water TDS is 334-364. With no DI, it's between 6-19 with recently replaced filters/RO.

The funny/strange thing is that my tank has been flourishing for the past few months that I've apparently been topping off with 6-19ppm water, and using that for WC.

I've had virtually no algae problems and great growth on pretty much everything - a clam, couple of bta, bunch of various lps, and softies.

So my question is, what are the likely/probable ions/particles that are in my post filter/RO, pre-DI water? And is there any risk of abruptly stopping with that "unwanted supplementation" for lack of a better term and getting new resin in my DI cannister?

Randy Holmes-Farley · Jan 21, 2015

In most circumstances, RO only is adequate to remove most problematic chemicals. The DI just provides that extra measure of security.

Silicate is one thing that gets through RO membranes, so if your water supply adds it, diatoms may become problematic (although I dose silicate).

If you had high copper in your house water, an RO alone might not be adequate, but most people won't have such high levels.

No, there's no risk of stopping. And I would, just to be safe (unless cost is a big factor).

cope413 · Jan 21, 2015

Nope, no issue. That seems like an absolute must. I just didn't want to immediately stop and have issues due to sudden drop in parameters that I don't currently test for.

Randy Holmes-Farley · Jan 22, 2015

Sounds good.

Good luck and Happy Reefing.

FishGuyTy · Jan 22, 2015

When you consider the very small amount of particulate, in this case 6-19 parts per million, there is no risk or benefit. Those concentrations are hardly enough for you TDS meter to measure, let alone your system. I can assure you that your livestock will not know the difference.