RODI ICP test shows silicon

[Dweezilz]

My ATI ICP test on my RODI water shows 12.79 µg/l of Silicon. I made the mistake of taking that sample from my Brute can that I had cleaned and just filled with all new RODI water instead of straight from the RODI. I have a Spectrapure Maxcap 90 with new sediment/carbon filters and membrane as of February. The Maxcap DI and Silicabuster DI are from last August and the Maxcap DI is still sending 0 TDS to the Silicabuster DI. TDS is 129-150 going in. I get 2 TDS out of the membrane. I have a 65 gallon tank so I have not used the DI's a huge amount.

So, question is, where did the Silicate come from? Could the brute have added it in some way? I cleaned it with citric acid, rinsed it multiple times, hand dried with a towel and and let it air dry for a few days before filling with fresh RODI. Could it be coming through the DI's even though TDS is 0? Lastly, is the 12.79 µg/l anything to worry about anyway? Not sure what to do besides waste 100 on new DI's.

 

[rtparty]

Maybe it came from the Brute (which is a good place to take the sample from if you are using that water for water changes and ATO) and I woudln't worry a ton about that level.

BTW the "Silicabuster" resin is just a marketing gimmick. It is some anion resin on the bottom and mixed resin on top. You can make it yourself if you really want.

I have silica in my tap water as well and the BRS 7 stage unit handles it with ease. Having the resin all separate saves money in the long run and has produced much better water for me. Might be worth looking into a second DI canister if the silica keeps getting past the current setup.

 

[DaveWrasse]

Maybe it's from ATI and not your RO? Try Reef labs ICP testing.

 

[certain_code]

As others have said if you are pumping your RO water from your Brute than that is the better water to be sent in for testing. If I understand this correctly you are reading 12.79μg/L which is roughly 0.0128 ppm of Silicon. This is well within a normal range for a tank as Triton ICP set point is 0 - 200 µg/l.

Where is it coming from? Well, it could be your source water or the Brute. It could also be the lines running to your tank. Ultimately the amount measured by your test is completely fine for your tank and instead, you should find out how to get that 2 TDS out of your source water as you are likely passing some other unwanted things along with your source water.

 

[Dweezilz]

As others have said if you are pumping your RO water from your Brute than that is the better water to be sent in for testing. If I understand this correctly you are reading 12.79μg/L which is roughly 0.0128 ppm of Silicon. This is well within a normal range for a tank as Triton ICP set point is 0 - 200 µg/l.

Where is it coming from? Well, it could be your source water or the Brute. It could also be the lines running to your tank. Ultimately the amount measured by your test is completely fine for your tank and instead, you should find out how to get that 2 TDS out of your source water as you are likely passing some other unwanted things along with your source water.

Thanks! The 2 TDS is out of the membrane and before either of the two DI's so based on my 98% rejection rate for the membrane it's expected. 0 after the 1st DI. I'll probably just ignore the tiny amount of Silicon for now and do another ICP in a few months and see how it goes. I guess I'll change the DI's in August at the 1 year mark just for good measure.

 

[Randy Holmes-Farley Verified Community Expert]

It is not uncommon to have silicate in RO/DI, even at 0 ppm TDS since it is one of the harder ions for the RO and the DI to remove.

It also is no concern unless you have diatoms bad enough to warrant an action.

I specifically dosed silicate to my tank, using far more than would come from your RO/DI.

 

[Miami Reef]

I purposely dose silica to my tank (about 1.5 ppm a week). I don’t have excess diatoms.

I dose silica to grow sponges and diatoms, which the latter feeds snails and copepods, and to increase competition to avoid things I don’t want (cyano and dinos).