First time poster - excited to use BBB method but have a question!

[PoolDoc]

1. Trichlor is, molecularly, a stabilizer molecule with 3 attached chlorine atoms. So, 100% trichlor does add stabilizer.

2. You can probably get away with lower chlorine levels in cool weather, but once water temps hit 70 degrees, you need to match your chlorine to your CYA level.

3. I found label info here: http://www.kellysolutions.com/erenew...1_26_02_AM.pdf

Your tabs are 80% trichlor, 10% borax, and 10% aluminum sulfate. The borax is fine -- it will keep the pH from dropping so much. The aluminum sulfate (alum) is OK . . . IF you have a sand filter. If you have a cartridge filter, you will need to clean more often. If you have a DE filter, you may also need to clean more, but I don't think the alum will hurt the filter.

This formulation does NOT contain copper, which is what stains pools.

[CarlD]

1. T
Your tabs are 80% trichlor, 10% borax, and 10% aluminum sulfate. The borax is fine -- it will keep the pH from dropping so much. The aluminum sulfate (alum) is OK . . . IF you have a sand filter. If you have a cartridge filter, you will need to clean more often. If you have a DE filter, you may also need to clean more, but I don't think the alum will hurt the filter.

This formulation does NOT contain copper, which is what stains pools.

I am guessing they are cutting the tri-chlor with cheaper ingredients that are not as destructive as others. Since tri-chlor tends to be very acidic, the borax would offset that, and, as Ben says, borates can inhibit algae. I don't know much about aluminum sulfate, but I am guessing it is a pH raiser as well.

[PoolDoc]

Carl, aluminum sulfate is an old-line floc and filter aid. It used to be fairly standard on commercial pools to feed small amounts of aluminum sulfate upstream of sand filters. It has the fairly unique quality of being able -- under certain conditions -- to tie up or capture metal ions. But I've never been able to find out exactly what those conditions were.

[CarlD]

Ah! I bow to your superior knowledge!
I'd still bet it helps reduce the production cost of those tri-chlor tabs...but, then again, I do have a cynical streak!

[PoolDoc]

I wasn't trying to say alum wasn't cheaper -- I'm almost certain it is, and that you are correct about their motives for adding it. I was just explaining what it does, and why it's a comparatively benign additive.

[chem geek]

A decent online source is poolgeek.com and they sell the following (prices are for 25 pound size) GLB 3" Trichlor tabs at a decent price ($91.14) and these are 99% pure Trichlor. You'll save even more if you can find these tabs in a local pool store since shipping is extra ($9.99 for 25 pounds). Other brands at 99% include Omni ($102.25), Robarb ($86.57 that appears to be the cheapest), ProTeam ($117.08).

[JimK]

A decent online source is poolgeek.com and they sell the following (prices are for 25 pound size) GLB 3" Trichlor tabs at a decent price ($91.14) and these are 99% pure Trichlor. You'll save even more if you can find these tabs in a local pool store since shipping is extra ($9.99 for 25 pounds). Other brands at 99% include Omni ($102.25), Robarb ($86.57 that appears to be the cheapest), ProTeam ($117.08).

I've ordered from PoolGeek many times and have been happy with them. They use to have the lowest prices on the things I ordered, but I've noticed the past couple seasons the prices have gone up.....still cheaper than local prices though.

[CarlD]

I wasn't trying to say alum wasn't cheaper -- I'm almost certain it is, and that you are correct about their motives for adding it. I was just explaining what it does, and why it's a comparatively benign additive.

I was just exploring the rationale for combining Borax and the alum with Tri-chlor. I also don't know much about it chemically.

[rdbrya1]

Sounds like I got ripped off royally LOL :-)
Around $99 for most 50lbs buckets of 99% Trichlor tabs and I paid $249 (!!!!!) for this bucket of "super" tabs that probably cost them less to make...ouch! This forum has helped me tremendously and I only found it a week ago. At least I feel safe using these tabs up until they are gone now that ya'll have explained the makeup of them so well. I wish I had found ya'll sooner!

[chem geek]

I was just exploring the rationale for combining Borax and the alum with Tri-chlor. I also don't know much about it chemically.

Let's look at the possible rationale and then blow holes in it, just for fun.

The rationale is to try and keep the pool clear since continued use of Trichlor builds up CYA lowering chlorine effectiveness so algae can start to grow faster than chlorine can kill it. When this happens, the water may not show visible green algae but instead look dull or cloudy. You already mentioned how Borax can help balance the acidity of the Trichlor and building up borates can help prevent algae. The aluminum helps to clarify the water so initial algae gets swept to the filter so if you backwash you get rid of it but if you don't clean the filter then it sits there using up chlorine and possibly continuing to grow.

However, with 80% Trichlor and 10% Borax and 10% aluminum sulfate, for every 10 ppm FC added by Trichlor the relatively small amount of Borax (I assume it's sodium tetraborate pentahydrate, not decahydrate) barely touches the pH and adds 0.2 ppm borates so at 2 ppm FC per day that's only an increase of 1.2 ppm Borates per month. So your assumption about it being more about "filler" may be accurate though there are less expensive fillers than borax. The minimum aluminum sulfate concentration for coagulation (as in DIN 19643-2) is 0.05 g/m^3 expressed as aluminum so for the example I gave there was 51.7 grams aluminum sulfate (4.08 grams aluminum equivalent) in 10,000 gallons or 37.85 cubic meters so this is 0.11 g/m^3. So while the addition of borates is of questionable value, the use of aluminum sulfate does appear to be in the ballpark at least after 10 ppm FC equivalent of chlorine is added (the alum gets caught in the filter so must be replenished).