Reducing Silicates (Without GFO?)

[Volcmreefer]

Derek, what was your pressure prior to installing the booster pump? I am running at 59-60 psi on the RODI (not sure where on it, it is a BRS unit). Would greater pressures increase filtration on the RODI? Thanks,

 

[Randy Holmes-Farley Verified Community Expert]

I have a very similar situation, for many months.
approx 400 silicate on Triton. salifert 0. seachem 0.
I tried rowaphos and silicat-ex at different times. But GFO kept my phosphate at 0 and caused me Dinoflagalette problems.

I got an triton ICP on my DI water at one point and it measured 1400. I resolved that by installing a booster pump on RODI unit.

Silicates still about 400 after several months. But I had to stop the GFO to get phosphates up and I have recently started dosing phosphates.

I will be sending another ICP soon, so I will be interested where silicates are at.

Just a reminder to folks that Triton and Salifert tests detect different things in the water.

Any actual diatoms in the water tested will give a signal for Si by Triton since its silica structure breaks up in the plasma into silicon atoms, but is not detected by a silicate test.

 

[Volcmreefer]

Thanks Randy. Is there another method/brand that give me a more accurate reading for silicate? I did see that HACH company has a meter but it’s pretty pricey. Thanks,

 

[Randy Holmes-Farley Verified Community Expert]

Thanks Randy. Is there another method/brand that give me a more accurate reading for silicate? I did see that HACH company has a meter but it’s pretty pricey. Thanks,

Every kit tests for silicate and not silica. I don't see a reason to think the Salifert could be missing large amounts.

In terms of the levels, whether silica or silicate, unless diatoms are at a problematic level from some aesthetic reason, the level is no concern.

 

[saltyfilmfolks]

I would buy some ornamental sponges.

 

[Macdaddynick1]

I've got a bit of a head-scratcher in terms of how I proceed with a slight silicate problem in my tank. I recently got back an ICP test from Triton which indicated I had high Silicon in the system (360 micrograms/liter), which normally I wouldn't really worry about as silicates aren't normally a big problem as I understand... But I have what I believe to be diatoms dusting the glass (cleaning daily, returning daily) and fluffy brown diatoms attaching themselves to the rockwork.

I purchased a silicate test kit from Salifert after getting the results from Triton so I could find the source of the silicates, but the tank registered a 0.00 which is disappointing because I know there are excess silicates in the water from the Triton test.

As I understand, GFO can be used to reduce silicates, which is great, but I'm currently trying to RAISE PO4 (from 0.00-0.01), so I feel using GFO would work one problem against the other. Any ideas on a workaround?

Possible causes of silicate source:
-BRS dry rock (cured in saltwater for about 3 months prior to adding fish/corals)
-Instant Ocean salt mix (standard, not Reef Crystals)
-RO/DI filters (all filters, including DI and membranes) replaced not more than 2 months ago, producing 0 TDS water, so pretty sure it's not that. Color-changing resin still mostly blue.
-Tank has been running for 8 months.

Let me know if I can add any other data that might be helpful. Ideally I'm just looking to find a way to use GFO (or any other silicate removal strategy) that won't deplete PO4 completely. I'd also obviously like to find the source of the silicates, but find it difficult if I don't have a reliable test kit for it.

I'm having the same problem. I just got my results from an ATI ICP they test both the tank water and RODI. My tank is showing high silicates (294.5 µg/l) , and it's coming form my RODI (29.77 µg/l) even though it's showing 0 TDS.

 

[Derek Clifford]

Derek, what was your pressure prior to installing the booster pump? I am running at 59-60 psi on the RODI (not sure where on it, it is a BRS unit). Would greater pressures increase filtration on the RODI? Thanks,

My mains pressure is 24psi. It is too low to direct feed the RODI. The pressure is not sufficient for the RO membrane to work effectively .
With the install of the booster pump I increased it to 80psi.

 

[Derek Clifford]

I'm having the same problem. I just got my results from an ATI ICP they test both the tank water and RODI. My tank is showing high silicates (294.5 µg/l) , and it's coming form my RODI (29.77 µg/l) even though it's showing 0 TDS.

You are probably aware that silicates do not conduct electricity. Therefore they cannot me measured with a TDS meter.

 

[Macdaddynick1]

You are probably aware that silicates do not conduct electricity. Therefore they cannot me measured with a TDS meter.

I honestly still have no idea what silicates are, and what they do. All I know is mine are coming from RO.

 

[Xclusive Reef]

I honestly still have no idea what silicates are, and what they do. All I know is mine are coming from RO.

How you know they coming from rodi?

 

[Macdaddynick1]

How you know they coming from rodi?

ATI tests your RODI mine has silicates

 

[Donavon]

Sponges will uptake silicates naturally, so I have read, seed your sump with them

 

[Randy Holmes-Farley Verified Community Expert]

You are probably aware that silicates do not conduct electricity. Therefore they cannot me measured with a TDS meter.

Silicate (Si(OH)3O-) is charged and conducts and is detected, as will its positively charged counterion.

If some of it is present as silicic acid, that won't conduct. The pKa is about 9.5, so at lower pH, most will be silicic acid.

 

[Randy Holmes-Farley Verified Community Expert]

ATI tests your RODI mine has silicates

Yes, but that does not mean it is the source of high aquarium levels. It is rapidly depleted. I routinley dosed very large amounts (equivalent to 840 ug/L Si) and it depletes to none detected in a few days.

If your RO/DI has 1000 ug/L Si, and you top off 1% daily, that boosts Si by 10 ug/L per day. In my tank, that would not show up.

 

[Randy Holmes-Farley Verified Community Expert]

I honestly still have no idea what silicates are, and what they do. All I know is mine are coming from RO.

I would not assume RO/DI is the source. It may be, but detecting some there does not prove it is enough to be important.

Here's the other info:

Feature Article: Silica In Reef Aquariums
http://www.advancedaquarist.com/2003/1/aafeature1

 

[Derek Clifford]

Silicate (Si(OH)3O-) is charged and conducts and is detected, as will its positively charged counterion.

If some of it is present as silicic acid, that won't conduct. The pKa is about 9.5, so at lower pH, most will be silicic acid.

Intetesting. In the case of my 3 TDS meters none of them detected the 1400 ug/l Si that Triton ICP detected.

 

[Randy Holmes-Farley Verified Community Expert]

Intetesting. In the case of my 3 TDS meters none of them detected the 1400 ug/l Si that Triton ICP detected.

That isn't much from a conductivity standpoint. 1.4 ppm Si. If it was 1.4 ppm sodium chloride, you might just barely detect it as 1 ppm TDS. .

This paper shows that silicate can be quantified by conductivity:

Determination of silicate in water by ion exclusion chromatography with conductivity detection
http://www.sciencedirect.com/science/article/pii/S0021967300000789

 

[Volcmreefer]

Well, now I am really puzzled. Tested my RODI water and my tank with the silicate test kit from Salifert and levels are very low. I went ahead and installed the MaxCap DI and SilicaBuster anyways. Running BRS high capacity GFO. I also purchased some Purigen and placed that in the sump under high flow. Any thoughts as to how this could be getting in my system? Is Silicon different than Silicate? Thanks again for everyone’s insight on this.

 

[Randy Holmes-Farley Verified Community Expert]

Well, now I am really puzzled. Tested my RODI water and my tank with the silicate test kit from Salifert and levels are very low. I went ahead and installed the MaxCap DI and SilicaBuster anyways. Running BRS high capacity GFO. I also purchased some Purigen and placed that in the sump under high flow. Any thoughts as to how this could be getting in my system? Is Silicon different than Silicate? Thanks again for everyone’s insight on this.

Silicon as detected by ICP includes all forms that are present in the sample. That would include particulates of glass and zeolites and related solids, diatoms (they have silica structures), suspended silicone materials, and soluble silicic acid and silicate. Triton says they remove particulates, but I do not know what sizes they remove, or how effectively.

 

[Volcmreefer]

Thank you Randy. I guess I will continue to monitor. I might take a sample of mixed saltwater and see what I come up with. Using IO right now. Although, if my RODI water is close to undetectable there shouldn’t be much in the saltwater mix, correct? I remember someone saying that silica can be consumed by the diatoms and sponges in the tank. I guess I will just have to wait and see...

Thanks again for all of your insight on this.