Need Help with Pool Chemicals

[James Watson]

www, one of the critical factors you need to manage is the CSI (Calcite Saturation Index). You should maintain a CSI of between -0.2 and +0.2.

You can use the pool calculator to calculate your CSI.

[floridapooltech]

James Watson, you are extremely, rude, immature, and confrontational. We are here giving out free advise and all you do is try starting an argument? If you "know so much", why don't you actually have the forum administrators set you up as a pool pro? Anyone can write just about anything right or wrong and place it on a website. it is proven that a fiberglass pool shouldn't have anymore than 120ppm calcium which they already have, yet you think the homeowner needs to go out and buy $100 worth of it for no reason?? Self proclaimed title with a shiny badge...I'm not even going to get into this as your are very immature. There are a few books you should be reading that we refer to. 1: NSPF "Pool & Spa Operator Handbook", 2: Taylor "Pool & Spa Chemistry", 3: Seaklear "The Book On Effective Water Treatment". When you read those 3 manuals, maybe someday you will grow up, act your age, and stop giving people the "wikipedia" advise that average people can write on google. If you haven't noticed, people come to this forum to get REAL advise as they know how reliable internet advise really is.

[chem geek]

Guys, please calm down.

As for the slug method or acid column method, this was debunked in this report that James referenced and this method doesn't make sense from the chemistry/physics either. Adding a lot of acid quickly can damage pool surfaces (I'd never ever do this in a vinyl pool, for example) and will not differentially lower TA vs. pH. Adding acid REGARDLESS OF METHOD lowers the Total Alkalinity (TA) where 25-1/2 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons lowers the TA by 10 ppm. That comes from the chemistry, pure and simple. What can happen is that carbon dioxide outgassing can cause the pH to rise with no change in TA, but there is no way to prevent a TA drop when adding a strong acid.

Of course, adding acid also lowers the pH so the way to lower the TA while not lowering the pH too much is to do aeration. The lowering TA procedure is described in this post. The slug method presumes that it can cause more outgassing of carbon dioxide due to locally low pH, but this process is not fast so it is safer and more efficient to lower the pH of the entire pool (and therefore it's surface exposed to the air) to 7.0 or so and increase aeration (pointing up returns, running a fountain, waterfall, etc. or splashing) which will cause the pH to rise with no change in TA. More acid can then be added to further lower the TA and the process repeated until the TA target is achieved. Then aeration has the pH rise with no change in TA.

As for the proper level of Calcium Hardness (CH) in fiberglass pools, this isn't crystal clear the way it is for plaster pools that clearly need the full amount to saturate the water with calcium carbonate (i.e. they should have a saturation index near 0) nor for vinyl pools that do not need it at all and do not need the saturation index to be higher. The gelcoat for fiberglass can contain calcium carbonate so to that extent some saturation of the water might be helpful to protect that gelcoat. As for cobalt staining, that is something that waterbear (a user on other sites with extensive experience and knowledge) had indicated that some CH helps reduce that though it didn't sound like full saturation was needed. So on this one, I'm not so definite with regard to fiberglass.

Richard

[James Watson]

Waterbear says that he keeps his calcium at 250 ppm.

The calcium is supposed to help prevent staining and to prevent cobalt leaching from the gelcoat. Cobalt staining is very common in fiberglass pools and looks like little black dots that seem to grow like a crystal. I keep mine at about 250 ppm. I used to keep it lower but I had iron stains more often. Since I increased the hardness of the water, I have had much less iron staining in the pool. Didn't even need to use any ascorbic acid this year! - Waterbear
http://www.poolforum.com/pf2/showthread.php?p=54560

And, the two fiberglass manufacturers that I referenced say that a higher level of calcium is needed. At a minimum, the warranty is an issue. The OP should find out what calcium level is recommended by the manufacturer of their pool.

[James Watson]

swimnsaveusa
it is proven that a fiberglass pool shouldn't have anymore than 120ppm calcium which they already have, yet you think the homeowner needs to go out and buy $100 worth of it for no reason??

Increasing the calcium from 130 to 175 would only take 5 pounds. How do you get $100.00? Is that how much you think it would cost? For someone who "claims" to be in the industry, you sure don't know very much.

Perhaps you charge 20 dollars per pound for calcium chloride, but that's ridiculous.

[Jsmoon]

This inflatable pools site has a guide claiming that bromine is just as usuable as chlorine. Is that really true?

[chem geek]

Bromine is a valid option but has its own set of issues. It breaks down in sunlight but unlike chlorine it isn't protected directly by Cyanuric Acid (aka stabilizer or conditioner). It's also generally more expensive, but for a very small pool that's not a big deal.