Surprising cause of elevated TDS

[Dom]

I have a bit of a Cyno problem in one of my tanks. This particular tank has a gravity-fed ATO system.

I tested PO4 and found that it is at 0.04.

As I prepared RODI for a water change, I tested a sample and found TDS to be at 80.

I watered the plants with what I made and flushed the RODI system for 10 minutes along with rinsing and drying the mixing basin.

After the 10 minute flush, my TDS reading came up ZERO, so I started making water change again. Several gallons into the new water, I tested TDS from the CLEANED mixing basin and TDS was still 80!

And yet, out of the RODI filter, it was ZERO.

Since it is a rectangular basin, I use an AquaClear 70 to circulate my water, which turns out to have been the source of the elevated TDS.

Who would have thought? I certainly didn't. But I was surprised to see what accumulated in the filter because I use it as an empty box and has no filter media... not even a sponge.

I'm back to using a submersible pump in the mixing basin.

Just thought I'd share.

Dom

 

[sghera64]

CO2 being dissolved into your RODI?

 

[ZoWhat]

So you were using a HOB filtration system full on with filtration media to circulate stored RODI?

I can understand water movement.but not understanding why you would filter RODI that's already 0 TDS = pure h2o

Good catch and glad you got it straightened out

 

[Dom]

So you were using a HOB filtration system full on with filtration media to circulate stored RODI?

I can understand water movement.but not understanding why you would filter RODI that's already 0 TDS = pure h2o

Good catch and glad you got it straightened out

It was one of those things where I needed to circulate new RODI during production and as a means of mixing salt to it. My submersible pump crapped out, so I hung the AquaClear 70 (a HOB filter) WITHOUT any filter media as I was only interested in mixing.

TDS was ZERO at all points until it touched the filter.