Silica Dosing/Testing Question

[Brandon McHenry]

Hi guys!

I am trying to grow sponges in a sponge dominated tank and I am trying to supplement them with silica. I have purchased Brightwells Spongexcel as well as Saliferts silicate test kit. I did the math and dosed the proper amount for the tank size but I can't detect it on the test kit. Is there a reason why my test kit would consistently read 0 even after I've dosed? I've checked the kit against tap water and I do get color change.

Any thoughts?

 

[Randy Holmes-Farley Verified Community Expert]

In general, I don't have a lot of confidence in Brightwell additives, but that isn't the most likely issue.

How much do you think you dosed?

How soon after dosing did you test?

 

[Brandon McHenry]

In general, I don't have a lot of confidence in Brightwell additives, but that isn't the most likely issue.

How much do you think you dosed?

How soon after dosing did you test?

I added 5ml of the product (which states is sodium silicate) to approximately 30gallons of tank water.

I tested the water about 4 hours after dosing and 24 hours after dosing. I got 0ppm both times.

 

[Randy Holmes-Farley Verified Community Expert]

How high is that supposed to boost silicate? Well into the detectable range of the kit?

It likely will drop fast and might be undetectable after 24 h when dosing a NSW equivalent amount:

Feature Article: Silica In Reef Aquariums ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/2003/1/aafeature1

from it:
Figure 4. The concentration of soluble silica as a function of time after dosing. Dosing was done at t=0. The concentration for t=0 (30 mM) is an estimate based on what was added and the estimated total system volume.

 

[Brandon McHenry]

How high is that supposed to boost silicate? Well into the detectable range of the kit?

It likely will drop fast and might be undetectable after 24 h when dosing a NSW equivalent amount:

Feature Article: Silica In Reef Aquariums ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/2003/1/aafeature1

from it:
Figure 4. The concentration of soluble silica as a function of time after dosing. Dosing was done at t=0. The concentration for t=0 (30 mM) is an estimate based on what was added and the estimated total system volume.

The 5ml that I added "should" have raised the concentration to 1ppm, which is definitely into the range of the test kit. I was able to detect 0.25ppm in my tap water using the kit so I know it works for lower levels.

I have read over that article and that is where I came up with the idea to dose for silica.

Even if the concentration drops rapidly over a few days, why would I still read 0ppm after only 4 hours? I just don't want to over dose looking for a color change on the test kit.

 

[Randy Holmes-Farley Verified Community Expert]

The 5ml that I added "should" have raised the concentration to 1ppm, which is definitely into the range of the test kit. I was able to detect 0.25ppm in my tap water using the kit so I know it works for lower levels.

I have read over that article and that is where I came up with the idea to dose for silica.

Even if the concentration drops rapidly over a few days, why would I still read 0ppm after only 4 hours? I just don't want to over dose looking for a color change on the test kit.

Could be any of:

1. The supplement is not what it claims.
2. The kit isn't giving accurate results.
3. The pent up demand by organisms is sucking it up fast.

 

[Brandon McHenry]

1. How would I determine if the supplement is not doing what it says it should?

2. Unless the kit does not work with saltwater, which I thought all salifert kits do, I don't know why I can get a tap water reading but not a tank reading.

3. I added 10ml of the spongexcel (enough to raise the tank up to 2ppm) and I read 0ppm less than 1 hour after the addition.

I'm really just lost and I want to make sure I'm giving my sponges everything they need since they look like they have declined slightly since I added them to the tank.

 

[Randy Holmes-Farley Verified Community Expert]

1. You can put some in fresh or salt water and see if you get the expected kit reading.

Salifert silicate works in salt water. But you may be using it wrong. lol

 

[Brandon McHenry]

1. You can put some in fresh or salt water and see if you get the expected kit reading.

Salifert silicate works in salt water. But you may be using it wrong. lol

I will try to add some to fresh and see if I get a reading.

I don't think I could be using it wrong if I can get simultaneous results in tap water.