SilicaBuster....

[USC-fan]

What makes this different from regular DI? Any other products like this?

[HighlandReefer]

When you have a one chambered DI filter you are using a mixture of two types of resins, anion resins and cation resins. The cation resins pick up positively charged ions. Silicate ions in water are negatively charged & are picked up loosely by the anion resins.

Perhaps the mixed bed resins sold specifically for silicate removal have more anion resins than cation resins in the mix.

The bottom line is as long as your TDS of the RODI effluent remains at zero, you are fine. Once your effluent starts to rise, you need to change your DI cartridge very soon since the silicate ions are held loosely and can be dumped all at once in rather large quantities. ;)

[USC-fan]

You are correct. I found they use 1/3 anion and 2/3 mix resins in the silicabuster.

[HighlandReefer]

Depending on the ions and their concentrations in your tap water, one mix of resins may work better for you than the other. The easiest way to tell IMHO would be to compare how many gallons of pure water each DI resin mix makes, before exhausted & the TDS starts to climb. It is possible that the SilicaBuster may become exhausted regarding TDS of the effluent more quickly & end up costing you more to use. ;)

[kzooreefer]

Silica in water does not always carry a charge, in some cases it is colloidal. If it is in the weak acid form it tcan be removed by a strong base anion exchange resin. I believe standard di cartridges contain only a weak base resin silica can pass through. If it is coloidal it will pass through any resin.

[USC-fan]

Would it show up as TDS? If I get 0 ppm with a good meter is there anything that would not show up?

[HighlandReefer]

Provided your RODI system is functioning properly there should be little to worry about as long as you get a zero reading. The carbon filter will pick up most dissolved chemicals tied with organics which can include silica & pesticides in that form for example. The RO membrane will prevent organisms & particles larger than a water molecule from passing. ;)

Reverse Osmosis/Deionization Systems to Purify
Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.php

From Randy's article:

However, at the small end of the spectrum a number of compounds can pass through a reverse osmosis membrane to some extent and are, therefore, of concern to reef aquarists. These include carbon dioxide (CO2), ammonia (NH3), hydrogen sulfide (H2S, especially a concern with well water) and silicic acid (Si(OH)4, which is the uncharged and predominate form of silicate at pH values below 9.5). All of these should be trapped by a functioning DI resin (discussed below), but can still be a concern.


What is TDS?
http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.php

From Randy article:

Since TDS meters are often used to test water "purity," it is important to understand what they do not detect. As conductivity meters in disguise, TDS meters will only detect mobile charged ions. They will not detect any neutral (uncharged) compounds. Such compounds include sugar, alcohol, many organics (including many pesticides and their residues), and unionized forms of silica, ammonia, and carbon dioxide. These meters also do not detect macroscopic particulates, as those are too large to move in the electric fields applied. So if you see "rusty" looking water from iron oxide particulates, that won't be measured. Neither will anything else that makes the water look cloudy. Bacteria and viruses also won't be detected.

[bertoni]

Do you have a specific problem you're trying to solve? If your source water is high in silica, a silica-buster type of cartridge might be useful. I agree that a TDS of zero should mean the water is fine for your aquarium. A small amount of remaining silica shouldn't cause any problems. At most, the tank might get a small amount of diatom growth, possibly resulting in less cyanobacteria, for example.

[USC-fan]

I think my Silica is high but I also have chloramines. Anion DI stage follow by a mixbed DI stage should help?

Thought about just not doing mix beds so a can easier reuse the DI also.

[bertoni]

The carbon block will deal with the chloramines:

http://reefkeeping.com/issues/2003-11/rhf/feature/index.php

I wouldn't worry about the silica, personally. Snails are happy to eat diatoms. I dosed silica into my tank for a long time.

[Buckeye Hydro]

If you have chloramines you'll go through DI resin faster than expected. You'd add cation resin to deal with this, while you'd add anion resin to deal with silicate ions. Sounds like a mixed bed...

Russ