Big Battle in Scale City

[TexasTwister]

Hi everyone,

Don't know if this is the right forum, so if not, please move this post! (Moved to Pool School)

Anyway, since pool startup in Sept. 2007, I have been fighting scale problems. The pool was never started up correctly by the the PB. Now that I've done my research, I know they did a poor job by adding only a couple of gallons of muriatic acid, no chlorine, and a quart of sequestering agent. They never performed a single test on water chemistry. The pool never really had a fighting chance to get rid of the "cream" on the plaster and I believe that was a building block for the scale to develop. Also, the PB told me that because I had a SWG, I did not need to worry about CYA because the system was constantly generating chlorine. "Why bother with CYA when you can have all the free chlorine you need?"

Boy was that poor advice. :x It wasn't until last week when I read the sticky "Water Balance tips for a SWG" that I finally realized what was going on. My months of fighting pH (8 - 8.2+) with gallons upon gallons of muriatic acid now made sense.

Since reading the sticky, I have boosted by CYA from 0 ppm to 60 ppm and my wild pH swings have subsided. Soon, I will be adding borax to get that protection in place as well. Now, I need to deal with the scale issue. In my situation, cost is a concern and therefore I have settled on a couple of different possible solutions:

One, Jack's Magic Stain Solution #2 Treatment (the copper & scale stuffâ„¢). I used this before with some success. Of course, I did this when I did not understand why I was having the big pH swings. (Stain Treat #2 Info). The scale came right back because I was not using enough sequestering agent (Jack's Magic Purple Stuff) to keep the silica from re-depositing itself. If the darn sequest test kit didn't cost $70 I probably would have done a better job of keeping the sequestering agent at 20 ppm.

Two, United Chemical's "No Drān Acid Wash" (No Drān Info). I have not tried this and I am not sure it is good for scale.

Unfortunately, the wind is outrageous today so getting clear pictures of the scale is not possible. I will post some as soon as possible.

Regardless, do you recommend either of these products, or is there an economical way to remove the scale (from an entire pool) with gallons of muriatic acid? I'm thinking that if I can get the pH into the sixes and TA into the 20's for a week or 2, and use my big stainless steel pool brush a couple of times a day, I would accomplish much the same as the 2 products listed above. This would be similar to this method (United States Patent 5045211) which I believe is the basis for United Chemical's product.

Thanks in advance everyone for your advice!

 

[The Mermaid Queen]

Sorry I cannot help you much, but someone here will know the answers. Sorry your PB messed things up, too, but you are in the right place to reclaim your pool.

Keep in mind that with an SWG, you will ALWAYS be fighting rising pH... just the nature of the beast. Most folks add acid weekly, if I remember correctly.

 

[JasonLion]

It would be nice to have a full set of test numbers for the pool and also the TA and CH levels of your fill water so we can advise you correctly.

High calcium and high PH leads to scaling. All of the treatments that you are thinking about take the calcium scale off the walls and put it in the water. To completly solve the problem you then need to get it out of the water so it doesn't just deposit back on the walls.

The low PH low TA approach will probably remove the scale inexpensively given that you don't have a heater. Jack's #2 is better but more expensive. Ideally you then want to replace some water to get the CH level down.

 

[TexasTwister]

Hi Jason,

Here is the data:

Fill water:

CH 140
TA 170

Pool water:

TC 1.5
FC 1.5
pH 7.4
TA 80
CH 290
CYA 50
Water temp 64

Thanks for your help.

 

[JasonLion]

Your levels are very reasonable right now, but as you take the scale off the calcium level will go up significantly.

Your fill water has some CH in it, but isn't so bad. It won't be too difficult to bring the CH level down by replacing water. However, the TA level in your fill water is quite high, which is likely to cause some issues.

High TA levels tend to cause the PH to rise and high PH is the leading cause of calcium scaling. Every time you add any significant amount of water to the pool you are going to need to lower the TA level. TA is lowered by adding acid, which lowers both PH and TA, and then aerating the pool, which raises PH without changing TA. The SWG will provide some aeration, but for major lowering of TA you will probably want some additional source of aeration.

Calcium scaling is really a function of quite a number of levels, PH, CH, TA, CYA, temperature, borates, salt, etc. High PH has by far the largest effect, but all of the levels are involved to one extent or another. You can get a sense of this by playing with the calcite saturation index calculation in my Pool Calculator, see the link in my signature.

Another factor to keep in mind is that as the plaster cures the PH, TA, and CH levels will all go up. Most of the curing will happen in the first three or four weeks, but the plaster will slowly continue curing for perhaps a year. Adding borates will slow the rate at which the PH rises to some extent, but so long as the plaster is curing you will have some PH increase. Monitoring the PH and keeping it from getting too high is very important. This can be challenging for the first couple of weeks, after that you should only need to check once every day or two and adjust it less often than that.

I would bring the CYA level up just a little more. 50 is alright, but 60-80 is ideal for a SWG. Keep in mind that it can take up to a week for CYA to fully dissolve, so don't worry about it if you added CYA recently.

 

[Guest]

If you live near an Ace Hardware that has a pool dept. and carries the O-Ace-Sis line they have a calcium hardness reducer that actually works! It also helps remove scale deposits. Follow the directions for initial water balance (pH above 7.8 ) and add a double dose of the product. pH should drop within a few days. If it does not add acid to lower it to about 7.2. Keep pH below 7.4 for a week or more (at least until the water clears since it might cloud). I've seen this lift scale deposits on more than one occasion and it's relatively inexpensive compared to the jack's magic.

 

[TexasTwister]

Hi Jason and waterbear,

Rest assured, I certainly intend of staying on top of my water chemistry during and after whichever pool treatment I use. Checking the fill water yesterday was an eye opener! Before then, I was not aware the fill water TA was so high. With an autofill system, the pool is constantly getting dosed with more TA, however TA has never been a problem. pH has been the big problem so far.

But back to my original question, which product or method would YOU use to knock down this scale? I could not find any Ace Hardware stores nearby that carry the O-Ace-Sis brand pool chemicals. I found it online, but you had to buy a case of 12 quarts (enough for 120,000 gallons)!

Here are some pics of the scale:

http://picasaweb.google.com/bret.and.ci ... qrC9LIS6oA

Thanks.

 

[JasonLion]

I would go with the Jack's Magic #2, but keep in mind that I am not very price sensitive. I have had great success with Jack's products but they are some of the most expensive on the market for what they do.

Also, remember that high TA can lead to high PH.