20 gallons of acid???

I am a new pool owner and have read many posts here. I now have a question.
22000 gal in ground, wet edge pebble sheen finish, Clean clear 420 cartridge filter 10 ft spa. on well water Flagstone coping

FC 2.0
tc 2.0
CH 150
CYA 60
TA 110
pH 8.0
tds 1000

well water tests 800 tds

startup 1 month ago 2 weeks in filter has tan buildup and pressure is 30. Cleaned filter and PB said he notices scale on the bottom of the pool and I should add metal free and jacks magic purple stuff to fix scale. I have been fighting the pH all along.
Now RB wants me to add 20 gallons of muratic acid to shut down pool and clear out the scale. the scale looks like to me about 1 foot in diameter in 3 places.

I am more than concerned about this acid bath.

When I had the water tested they suggested to get the CH up first then add another chemical to handle the scale problem.
I am also seeing sand appear and am guessing it is from the flagstone.
Any suggestions would be appreciated.
Thank you

I can't answer your question, but I also would be more than concerned about putting that much acid in my pool. However, my pool is a liner pool, so some of the other folks with experience with your pool finish should be by shortly and hopefully can give you some useful information.

I do want to remind you, though, that you're going to need to do whatever has to be done in order for them to warranty your pool, if you're still within the time period--even if that advice differs from what you read here.

Hi RCCI:

With THOSE numbers I doubt it's scale at all...more like some kind of algae! Scaling occurs when your CH and TA levels are too high, and that's not the case Let's look at those numbers again:
FC 2.0
tc 2.0
CYA 60
pH 8.0
CH 150
TA 110
tds 1000

I see CYA= 60 and FC=2 AND pH=8! Whoa! Our Best Guess table says that when CYA is between 60 and 90, you MUST maintain FC between 5 and 10ppm, and shock at 20 ppm. On top of that, chlorine is LESS effective when pH is too high, as yours is at 8. You would have NO problem growing algae in that!

Further, recommended levels of CH in hard-sided pool like yours is 200 to 400ppm, and you're BELOW that at 150 and TA is 110 (and, if pH was where it should be, TA would be even lower), well within recommended levels. I don't see how you can have scaling.

The only other possibility I see is a high iron or copper content, which the TDS score MAY indicate, but I have trouble believing that. Even so, 20 gallons of Muriatic Acid isn't the correct treatment.

I'm betting you have an algae bloom, plain and simple, and the test numbers agree with that. They do not agree with calcium scaling to the best of my knowledge.

Unless this PB is known for standing behind his pool, I would not consider adding 20 gallons of acid unless he instructed me to do so in writing...otherwise..."No yeronner. I never said put 20 gallons o' acid in. Nobody in his right mind would tell a pool owner that..." and it's your word against his.

Meanwhile, we have some commercial and metal content experts here and they can look at this thread and tell better if the PB is on target or flat-out nuts.

Carl.

I assume that this is a new plaster pool and that the pH has been constantly high because of the curing plaster. In that case it very possibly is scale deposits and adding acid would be called for but NOT 20 gallons, IMHO. I would not think that more than about 3 or 4 gallon max would be needed. Even if your PB used an acid startup to expose the aggregate the amount of acid used in a pool your size would only have been about 10 gallons!

FWIW, depending on how the pH is being testing it is very possible that the pH has been above 8.0 since many test kits cannot test above that (and pH above 8.0 is not uncommon with new plaster).

It sounds like your pool builder wants to do a no drain acid wash but the amount of acid he wants to use does seem excessive to me. What exactly does the scale look like. Also, the 'tan buildup" in the filter--put a bit of diluted acid (dilute about 4 to 1 or so) and let us know if it fizzes and bubbles. If so it is most definitely scale. If not then it isn't. Also, the 'sand' in your pool might not be from the flagstone but is most likely plaster dust from the new plaster and it is very common with a standard startup (as opposed to an acid or bicarbonate startup).
the
I would also be interested in the CH and TA of your well water. Remember, that scale is calcium carbonate so if it is depositing on the pool and filter surfaces it means that there is LESS calcium and TA in your water! Once again, your are probably seeing plaster dust in the filter and this is also common with new plaster startup.

Scale is a likely possibility with new plaster but I question the need for 20 gal of acid in a pool that size and would be concerned about equipment damage!

Finally, when you say "wet edge pebble sheen" finish are you referring to a negative edge pool with a
Pebble Sheen surface (Pebble Sheen is a product made by Pebble Tec) or are you referring to one of the Wet Edge Technologies pool finishes (a competitor of Pebble Tec and they do not make Pebble Sheen but their equivalent product is Satin Matrix)? The reason I ask is if you have a negative edge pool that would cause your pH to constantly be rising and would certainly contribute to scaling with new plaster.

Have you been brushing your pool daily? That is very important during the startup period.

On stuff like this, I always defer to Evan. But I still think a pH of 8, an FC of 2 and a CYA of 60 is an open invitation to an algae bloom.
However, Evan's acid test of the tan on the filter is, well the "Acid Test" of whether it's scale or algae.

Carl

Thanks for all the responses. The PB told me to go get the acid and he would "shut down" the pool today. I asked him to wait till swimming season was over for this which he said would be no problem. I have the CH up to 210 now and the scale seems to look like it is smaller. You guys are saying the same thing the chemical store said thats why I halted the acid bath. The Ph has been a problem but there seems to be no copper or iron on the water tests. Sorry for the confusion on the Wet edge, It is actually the Satin matrix pebble finish. I am going to try the acid on the filters tonight.
Thanks again for all the help.

Missed a couple of responses. The scale is white splotches and a patch about 2 feet across. Thats the big place a couple of small places as well but not the whole pool The plaster is new but the 8.0 ph was from the water test at the pool store.
Thanks again for all the help.

Filter update. Filters boiled in the water acid mix. Cleaned better than they ever had. I have had to clean them once a week to keep the pressure down. Lets see how that does. PB says it is the well water we filled the pool with. The well water is not the best. I have been brushing the pool 2 to 3 times a day for the first couple of weeks 1 or 2 times a day since. I will have the water tested again tomorrow and see the results. Working on CH now, ph and fc look good. I will post numbers tomorrow. Thanks again!!!

It's not the well water, what you are experiencing is very common on new pool start up when the startup method is standard startup and not acid startup. The bicarbonate startup method, which is the other way to start a new plaster pool, is only suitable for marcite and not for aggregate finishes if I am not mistaken so I am going to assume your builder did a standard startup procedure and because of the scaling is going to do a modified acid startup to dissolve the scale.

Thanks again for all the input. I have the latest numbers just to update the post. I spoke to the plaster installer and they recommended against the 20 gallons of acid just as you all did. The areas of scale are still smaller than before.
FAC 4
TAC 4
CH 200
CYA 99
TA 80
pH 7.6
TDS 1450
Pho 300

Thanks again for the help.