fiberglass, slight yellow whole pool stain/coating

[jonnygib]

I have a salt water, fiberglass, that holds 17,000 gallons. Any more help would be appreciated.

[mbar]

You can use Jack's Magic the purple stuff is made especially for salt water pools. Otherwise you can do the ascorbic stain treatment as posted above, except I would turn the salt generator off until after the treatment is finished and the water is rebalanced. Feel free to ask any other questions you have

[jonnygib]

I'm the original poster here. I have a 17,000 gallon pool and used ascorbic acid to remove the yellowing. About 10 days later the yellowing is starting to re-appear. So, as asvised I purchases some Jack's magic and am waiting for it to come in. The question that I have now is...how much of Jack's Magic should I have purchased. when I contacted Jack's Magic website, this is their response, but I wanted to check here before I bought more. I have one on quart on the way.

Reply from Jack's Magic...
"Jon you need to put 2qts of purple stuff in your pool.

Then you need to prevent them from coming back. You need to put 12 to 16
oz a week to prevent them. If you would like you may buy a sequesting
test kit for the correct amount of purple stuff you need weekly in your
pool. it takes 3oz to raise your level 1ppm. If you have anymore
questions I may answer for you feel free to call us Thanks

John Virga
customer service
(800)348-1656 EXT 111"

So, my question is, do you all agree with the response from Jack's Magic?

Thanks,
Jon

[mbar]

I have never even heard of a sequestering test kit - but there are a lot of things I have never heard of I do know however, that Jack's Magic tends to use more product than is really needed. I would suggest buying some - and just watch for stains - when you see some forming, take your ph down to 7, and add 1/2 bottle. I don't do a matainence dose, I just watch - sometimes even just taking your ph down will lightnen the stains. You will get your own routine down after a while. I always keep some ascorbic acid on hand too - this way if the sequestering agent and low ph don't work on the stain, I add a little ascorbic right down the side where the stains are noticeable and let the water circulate - most of the time there isn't much chemistry change. Just make sure you keep your ph at 7 - 7.4 with a fiberglass pool - I find with my pool, when the ph gets above 7.6 I start to see stain. Hope this helps - I am sure Jack's Magic really knows about stains - and can get you to keep a stain free pool, but it does get to be expensive using all that "purple stuff", when it may not be needed.

[jonnygib]

Thanks Marie. One more question, is their a cheaper alternative to the purple stuff that I should consider?

[mbar]

I think they are all about the same - there are cheaper ones, but with a fiberglass pool you need the better ones. I ususally look for something online that is on sale. Some of the good ones are Proteams Metal Magic, Metal Free, & Sequasol. There are more too, but I can't think of the names Right now I am using proteams metal magic and it works really well. This and Jack's Magic are my favorites so far.

[jonnygib]

Thanks Mbar. Your help is very much appreciated. I'll keep you updated on how it goes.

[waterbear]

You will need about 1 and 1/2 quarts of the purple stuff (or any other HEDP based sequesteant that uses 1 qt per 10 k gallons) initially. You might need to add a maintenance dose weekly, every two weeks or you might be able to get by with a monthly maintenance dose. I would start doing it weekly for a few weeks and then slack off to every two weeks. If the stains start to reappear go back to weekly. A lot depends on your chlorine levels, which can break down the sequstering ablility of HEDP. If you are staying stain free on a two week schedule then try only adding the maintenance dose monthly.

For a lower priced alternative I have had good results with Proteam's metal magic but even a ''house brand" will be equally effective. You want the active ingredient to be HEDP or phosphonic acid or a phosphonic acid derivative. If the ingredients are not listed on the label consult the MSDS for the product.

As far as testing sequesterant level in the water, Jack's Magic has a test kit for it (very expensive, IMHO) but it really is not necessary in most cases. LaMotte also has a sequestering agent test kit available for pools. Taylor has test kits but they are made for the boiler/cooling market and not for pools and are extremely expensive.

If you just observe your pool and learn how often you need to add a maintenance dose to keep your pool stain free you don't need to test.
My pool only needs a HEDP based sequesterant monthly but if I use an EDTA based sequesterant such as MetalFree I need to add it weekly or every two weeks.

Edit: If the staining is not extensive you can often eliminate it with a double or even triple dose of sequesterant and by dropping the pH as stated earlier in the thread. Put the sequesterant in first and test the pH since the sequesterant will drop the pH some on its own. This is usually more expensive than treating with ascorbic acid but it does not cause the chlorine demand problem. It just eats up the TA!

[Sumo1]

I've just started reading this thread and don't mean to get in the way but there may be others wondering like me--what does a sequestering agent do? My gunite pool has has an old plaster coat with several stains but I never really thought I could remove them so I just dream of a new plaster job.

[waterbear]

I've just started reading this thread and don't mean to get in the way but there may be others wondering like me--what does a sequestering agent do?
A sequestering agent 'deactivates' metal ions in the water so they don't cause staining or, in the case of calcium (which is also a metal), scaling.
My gunite pool has has an old plaster coat with several stains but I never really thought I could remove them so I just dream of a new plaster job.

It is possible to remvove certain stains from plaster but sometimes the process can take a while.

This thread has some more information about sequesterant and chelating agents and reducidng agents.