Scale on Fiberglass Pool

[HankDfrmSD]

My pool service added Sodium Bicarbonate to my pool, and shortly thereafter, a gray coating appleared on the fiberglass surface. That was six months ago. It has gradually lessened, but is not gone. My pool guy says just wait.

Any suggestions to speed up the process?

[CarlD]

The thing is, several things could cause that, but my first guess would be too much calcium in the water and adding the bicarb raised the Total Alkalinity so it started to scale.

BUT

That's impossible to tell without a full set of test figures.

We always recommend, first, the Taylor Technologies K-2006 or K-2006C test kit, but a good, cheaper alternative is the K-Mart HTH 6-way drop test.

While we will need tests for chlorine levels (preferably separate tests for FC--free chlorine, and CC--Combined Chloramines) and Stabilizer/CYA levels, what may confirm my initial guess is three tests:
pH--remember HS chemistry?
CH--Calcium Hardness
TA--Total Alkalinity--NOT the same thing as pH

[PoolDoc]

Read the muriatic info page => http://pool9.net/ma/, then get a jug of muriatic. (Lowes, etc.)

Pour a small amount of MA in a plastic bucket -- watch for fumes! Put the bucket next to the pool near a scaled spot. Wet the deck down, so acid splatters don't mark the deck; leave the hose running next to you, so you can quickly rinse away splatters.

While wearing gloves and glasses, wet a clean plastic sponge (no residue to react with the acid, and no cellulose sponges!!) with acid. Take the sponge, and hold it against one of the scaly spots. If it fizzes or is removed, lowering your pH will accelerate scale removal.

If that works, then read about lowering alkalinity, here: http://pool9.net/alk-step/

Meanwhile, if you can, purchase a K2006 testkit. With the pool guy you've got, you need one so you an monitor his actions. http://pool9.net/testkits/

[HankDfrmSD]

My pool guy has just provided the following readings:
Ph: 7.0
CA 300 ppm
TA 30 ppm
FC: 7.0

He used a drops test kit, and I believe his readings.

He wants to raise the TA to 120, suggesting we add 3lbs of Sodium bicarbonate. What do you think, Carl?

[PoolDoc]

Don't do it, if you still have scale!!

[HankDfrmSD]

Carl, any comments from you?

[PoolDoc]

Hank,

You've got our advice. It's up to you to decide who you trust: us, or your pool guy.

Good luck.

[HankDfrmSD]

Ben, my problem is that I'm not really sure whether it WAS scale. I am hoping to get some help here as to what to do. If I did not trust the advice here more than that of my pool guy, I would not be here. Carl asked me to get readings, and implied that if I did, he would give me his opinion. I got the readings and posted them here, but have not heard from him. You have told me what NOT to do, but I am asking for help as to what TO do.

I do not have the privilege of posting attachments here, so I have posted photos I took of my pool yesterday on Photobucket. Would you, and anyone else who reads this give me your opinion as to what this is?

http://preview.tinyurl.com/mrhvccp

[PoolDoc]

I see the photos, but they aren't sufficiently high resolution for me to have any clear idea of what you might have.

You are in Hawaii, so getting a K2006 may be hard. Can you get this kit from Walmart? http://pool9.net/hth-6way/ (Unlike you, I do NOT trust your pool guy's reading.)

It's going to be hard to put Vitamin C or Iron Out on those spots, since they all seem to be on the wall. Can you get a sink plunger like this one on Amazon http://ecx.images-amazon.com/images/I/31%2Bn10lD0EL._SY355_.jpg
to stick to the wall? You'd probably need a wooden handle one, so you could unscrew the handle.

If you can, put a handful of Vitamin C tabs in the cup, and then stick it (or hold it) to the wall for 15 minutes or so. See if there's any change. Do it again with 1/2 cup of Iron Out. And do it a 3rd time with pH Down (sodium bisulfate), but don't leave it there longer than 5 minutes.

See if any of those produce a change.