Cheetah is Losing Its Spots

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D

DanWL

0
Oct 6, 2015
8
Fernandina Beach, FL
Pool Size
10000
Surface
Plaster
Chlorine
Liquid Chlorine
Thanks to everyone for creating the best Pool site on the Web. My pool’s chronic Cheetah-like bottom/side stains appear to have been tamed to a great degree by following TFP’s advice.

My situation/question: I’m at the one week post AA treatment point when the Ascorbic Acid is exhausted and FC has re-stabilized. After re-shocking the pool last night from 2ppm to 12 ppm (one week post AA treatment - great results), my pH naturally rose from 7.0 to nearly 7.8. Now, I’m concerned the pH spike may release metals.

What’s a safe method to decrease pH quickly to 7.0-7.1 after a AA treatment / post AA treatment shock? Today, I precautiously added one pint of M. Acid mixed in 5 gal’s of water followed with sequesterant, about 1/4 of the recommended M. Acid dose by Taylor’s test kit. No stains have reappeared after adding one pint of M. Acid.

Recent Pool history:

I keep my FL pool operational all year. On April 4th, I changed 1/3rd of the water to reduce an elevated CYA of 60.

After the water change, my pool had the typical Cheetah stains. Following TFP’s CYA/Chlorine table, I shocked the pool to 20 ppm for one week while adding Poly60/sequesterant liberally, and brushed daily with a nylon Wall Whale brush. Filter cartridges are frequently changed. Persistent stains suggested metal staining, too.

On April 13, I treated metals with 1 pound AA/sequesterant (great results). I kept the FC at 1-2 ppm and waited a week to shock until the FC became stable, demonstrating the AA had finished reducing the FC.


Today:

Water temp: 76, Water clarity: Perfect, Bottom/Sides: Stain-free appearance, CYA: 30, FC dropping: 8, CC: 0, pH: was 7.0 yesterday. Now 7.8 (shocked last night liquid 8.25% bleach to 14 ppm), TA: 40, CH: 400


This April, I’ve used one quart each of Biodex and Suncoast’s Ultra Metal Sequesterants, and have a 4-pack of the less expensive and recommended Blue Wave Super Rust and Scale to test soon. A 4-month old CUlator 4.0 was opened and stained greenish-blue and a new one added to the pump’s basket this week. It appears to collect free metals as advertised.

Added note: Myspicesage. com also has good prices on bulk, food grade Ascorbic Acid. The indoor storage life is said to be very stable. My 5 pound order arrived in one pound sealed packages.


A big Thank You from my pool to Yours.
 
duraleigh said:
Welcome to the forum. :wave: There is no reason not to add ALL the acid directly without dilution. Please share with us how you came upon the info to dilute in such small increments?
Click to expand...

Duraleigh, Thank you and this morning, the pH had self-corrected to 7.0 with one pint added yesterday. Yesterday, Taylor’s pH acid demand test recommended adding 1.72 quarts of MA based on 10 drops in 10K gallons.

I added a larger dose of MA a couple years ago to correct a high pH and it seemed to release metals. Where the MA was poured into the pool, the pool water quickly changed to a reddish-brown color. It asked a local pool store and they felt the reddish brown color was released metals. They recommended the smaller incremental dosing.

Would you have gone with Taylor’s 1.72 quart MA recommendation and allowed the pH to settle ? I recently learned here that a short pH exposure in the 6.XX range should be safe. I was likely being over pre-cautious.
 
It is true that a rapid rise in PH can cause metal to precipitate into the water. If the water turns brown again stuff polyfill material into the skimmer baskets and it will grab the iron.

You can also use Poolmath to calculate/validate the dosage based on a target of 7.2.
 
Thank you Pooldv,

I’ll proceed carefully as the summer daylight extends and chemical demands increase with warmer water. Over the previous few years, I had tried different algaecides with disappointing results. Poly60 has made a significant impact on algae over the last month combined with the CYA/Chlorine daily residual and shock recommendations.
 
Sometimes higher chlorine levels, between target and shock level for CYA, can also cause metal to precipitate. Many algaecides contain copper and could be the source of your metal. There is no better way to control algae than to maintain your FC at target for your CYA, Chlorine CYA Chart, and Pool School - SLAM - Shock Level And Maintain if you do get some algae.

You can order this kit for 10 bucks to try to identify the stain source, Jacks Magic Stain Identification Kit JMSTAINID at Sunplay

Edit: just reread and copper seems to be the source of your stain. Nice work.
 
pooldv,

I reviewed both TFP pages and the Pool Calculator is very helpful. Polyfill material was a nice pre-cartridge recommendation for iron and occasional use as a general pre-filter. Jack’s ID Kit may be very helpful in the future. I also read in Taylor’s instructions that high calcium levels may effect metal control.

With hopes to reduce/eliminate skimmer plugs adding CYA 24/7 and powdered shock adding more calcium, I recently started using 8.25% liquid chlorine at dusk. If possible, I’d prefer to use liquid chlorine exclusively as a sanitizer while balancing the ideal CYA and Poly60 levels.
 
Danwl, kudos on nailing the stains. If you don't mind my asking, why did you shock/slam after the treatment at all? With knwn metals, if you don't need to (eg visible algae or failing an OCLT) its best avoided.

Slamming also rapidly consumes metal sequestrant. In your shoes I would consider adding at the very least a top up dose to keep the metal in solution. What kind did you use during the AA treatment?

(Since you're using polyquat, DON'T use Jack's Magenta...any of the other Jack's or Metal Magic would be fine (hedp) )

Cheers to "cheetah" removal ;)
 

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I used one quart each of Biodex and Suncoast’s Ultra Metal Sequesterants during and after the 1 week AA treatment. I likely over responded with the post AA treatment shock dosage. The reason is I wasn’t using poly60 concurrently during past AA treatments and had quick algae blooms on low chlorine doses alone. I added extra Suncoast Ultra Metal around the edges and it quickly reabsorbed the released metals.

This time, generous doses of POLY60 before, during and after AA treatment prevented the algae bloom. Moving forward, I’ll limit the post-AA chlorine treatment to the correct Target ppm based on the CYA level. Now, I’m testing a 4-pack of the less expensive and recommended Blue Wave Super Rust and Scale. It seems to be working well, yet, it’s the first sequesterant I’ve seen that recommends night time dosing for best results. Out of Jack’s Magic sequesterants, it appears the Pink formula may be the best for my pool.

I may have succeeded attaching a photo of a four month old CUlator 4.0 removed and cut open from the pump strainer basket. I added a new one. CUlator said a 4.0 should last about 3-4 months in my 10K pool. Originally, I think it may be a whitish color.

- - - Updated - - -

Thanks pooldv. Please see the next post for a photo of a four month old CUlator 4.0 removed from the pump stainer basket.

- - - Updated - - -

I may post this twice - thank you and see the photo of the 4 month old CUlator a couple posts down.
 

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Thanks to all. To help keep track on everything TFP, I’m logging all pool treatments on a dedicated, large wall calendar. In addition to pool chemicals added, it includes water chemistry levels, pool appearance, water temp, partial water changes, CUlator installation date, filter changes, big pollen blooms blowing in, and anything else I find helpful.

I started it in April and it’s been updated nearly daily. A dedicated TFP Pool calendar has proven to be a very useful reference for me personally.

- - - Updated - - -

Thanks to all. To help keep track on everything TFP, I’m logging all pool treatments on a dedicated, large wall calendar. In addition to pool chemicals added, it includes water chemistry levels, pool appearance, water temp, partial water changes, CUlator installation date, filter changes, big pollen blooms blowing in, and anything else I find helpful.

I started it in April and it’s been updated nearly daily. A dedicated TFP Pool calendar has proven to be a very useful reference for me personally.
 
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