How Do Tank Clarifiers Work?

[eatbreakfast]

There are a number of products such as Brightwell Clarifi SW and Fritz Clarifier among others that claim to bind particles. Brightwell specifically mentions utilizing a weak electric charge of particles. My question is what exactly are they using, and besides binding particles what effect, if any, would it have on water chemistry, particularly the main chemical agents that are commonly added to reefs, as well as it's affects on bacteria.

 

[Randy Holmes-Farley]

Water clarifiers generally work by binding together the solids floating in the water, causing then to preciptiate from solution. Most often, this is accomplished by using some material that has multiple charges opposite to the net charge on the particles.

For example, a molecule with a lot of positive charges on it can act as a bridge between particles with negative charges, binding them together. Many of the particles we encounter in reef tanks have net negative charges (see link for seawater sources):

http://www.aslo.org/lo/toc/vol_17/issue_1/0007.pdf
from it:

"The surface charge of particulate matter in seawater from estuarine and coastal sources was investigated by microelectrophoresis. Seston consisting mostly of bacteria, small algae, and detritus exhibited a considerable range of mobilities but all were negatively charged;

The overall process is described in detail here:

http://www.gewater.com/handbook/ext_treatment/ch_5_clarification.jsp

Water clarifiers used in the aquarium hobby (fresh and salt water) include alum (aluminum sulfate), organic polymers with lots of positive charges, and whole bacteria. I do not think the aluminum is a good choice in seawater, not only for potential tox reasons, but because it quickly binds hydroxide, reducing alkalinity and loosing its three positive charges.

The bacteria (sold by Dr. Tim's, for example) could be a bit more complicated, and I'm not sure what net charge the bacteria they use have. They may also work partly through hydrophobic interactions.

I do expect that clarifiers tend to bind up some of the free floating bacteria from the water.

 

[Randy Holmes-Farley]

FWIW, Brightwell doesn't say what is in either their freshwater or salt water versions, but one might speculate that it is aluminum in the freshwater version and an organic polymer with positive charges in the marine, but I really do not know.

 

[biom]

Both of them using polymers called polyelectrolytes to initiate flocculation (precipitation) of the fine particles using its weak electrical charge. It is good question how they will effect water chemistry, but there is no information exactly what kind of polyelectrolites they are using. They could be of natural origin and less dangerous to reef since they will be utilized by bacteria, but I doubt.

 

[bobbyM]

Products like these are a bad solution to the problem they claim to fix. IMO

 

[eatbreakfast]

Thanks, I have been reluctant to trust them in a reef because all their explanations are so vague.

 

[biom]

Fortunately there is better and totally harmless flocculant - calcium carbonate powder (KZ Coral Snow), that I'm using every other day DIY version

 

[Myka]

Fortunately there is better and totally harmless flocculant - calcium carbonate powder (KZ Coral Snow), that I'm using every other day DIY version

I've heard some people say that Coral Snow is likely Calcium bentonite. I'm not sure if that's true or not, but wouldn't that make more sense than Calcium carbonate?

 

[biom]

I've heard some people say that Coral Snow is likely Calcium bentonite. I'm not sure if that's true or not, but wouldn't that make more sense than Calcium carbonate?

It is carbonate, I've done simple analysis and posted in Reef Central some time ago. May be is good to start new thread here. Actually it is chalk, not pure calcium carbonate (there are some magnesium etc.) and it is about 400 grams in 1 liter RO water.
Way do you think bentonite is better than calcium carbonate? Bentonite is aluminosilicate just like zeolite and I don't really think it is good idea to spread fine particles containing aluminium in a reef tank.

 

[Myka]

It is carbonate, I've done simple analysis and posted in Reef Central some time ago. May be is good to start new thread here. Actually it is chalk, not pure calcium carbonate (there are some magnesium etc.) and it is about 400 grams in 1 liter RO water.
Way do you think bentonite is better than calcium carbonate? Bentonite is aluminosilicate just like zeolite and I don't really think it is good idea to spread fine particles containing aluminium in a reef tank.

Yes, I'll go make a new thread.

Here it is: http://reef2reef.com/threads/is-coral-snow-calcium-carbonate-or-calcium-bentonite.231668/

 

[Randy Holmes-Farley]

Both of them using polymers called polyelectrolytes to initiate flocculation (precipitation) of the fine particles using its weak electrical charge. It is good question how they will effect water chemistry, but there is no information exactly what kind of polyelectrolites they are using. They could be of natural origin and less dangerous to reef since they will be utilized by bacteria, but I doubt.

Yes, I agree they say that, and if technically correct, neither would be aluminum. I just worry that some companies try to hide the true nature of their products with somewhat misleading words.

Anyone have a thought on why the polyyelectrolytes in the two Brightwell products (fresh and salt) would be such that they are not to be used in the other (salt or fresh)?