First pool, water is clear but fiberglass is stained and lots of scale

[MountainStone]

Just purchased a house in Vegas that has a 7500 gal fiberglass Renaissance pool. The house was a foreclosure and the pool water got very low and very disgusting. It was purchased by a 'flipper' who got the house/yard/pool into good shape and I bought it.

When I purchased, the pool was full of clean water but there are some brown stains on the bottom and sides of the pool. On the sides, the stains have a definite line where I assume the waterline was at the low-water mark. There are no stains above that line. I haven't gotten into the pool yet but a brush on a pole doesn't affect the stains at all. I assume they are stains on the gelcoat from the yucky water, but how do I remove them? Wet sanding?

Also, there is a chalky white substance at the waterline all around the pool. The water here in Vegas is VERY hard so I assume this is deposited calcium/minerals/what-have-you. I tried scrubbing it off with a sponge to no avail. I purchased a product from the local pool supply dealer (Descale-It with glycolic acid) which helped a little but has not eliminated the scale even after 3 applications and scrubbing with a Magic Eraser. And I mean SCRUBBING, as in 80 passes per square inch. Any advice?

P.S. The water chemistry has been maintained properly (to my limited understanding) and is still clean and sparkling.

Thanx!

[PoolDoc]

Hi Stone;

1. Put some scale in a glass with white vinegar. Cover it with Saran wrap and leave it overnight. If it bubbles or dissolves, it probably carbonate based and can be cleaned up with various acidic products. If it doesn't do either, it may have to be removed mechanically.

2. Put a Vitamin C tablet on a stained area. If the area is lightened when the tablet dissolves . . . it's a metal based stain. Otherwise, it's not, or at least, probably not either copper or iron. Organic stains can be left from "yucky water", and are frequently removed by high chlorine + time.

3. Quote: "the water chemistry has been maintained properly". Our ideas -- BBB method ideas -- about what "properly maintained water" is, and standard pool industry ideas about it vary from each other quite a bit. Get a K2006 (link to Amazon, or you can search Google). Be SURE to get an FAS-DPD chlorine test; the K2005 is NOT the same!

Let us know what you find.

[MountainStone]

Thanx Doc! I've been reading for hours; great place you've got here. The white flaky stuff foams when I spray on the acid, it's just incredibly resilient and I have yet to completely dissolve/remove it with either application of acid or scrubbing with the mildly abrasive Magic Eraser. I was hoping for a suggestion that requires only one application and/or a lot less elbow grease.

Regarding the brown stains on the bottom and sides of the pool: I will try the vitamin C tab.

Regarding the water chemistry: I will order the recommended kit. A lot of reading here has enlightened me as to the prevailing forum philosophy; I am so pleased to have found this place and pleasantly surprised at the level of commitment from the moderators. Thanx so much for helping!

[PoolDoc]

Ok, if it's calcium, do this;

1. Get the K2006 kit (links in my sig) and get test results on BOTH your pool, and your fill water. Do NOT test the fill water for CYA; there's none there and there are only a few CYA tests in the kit. The links go to Amazon, but if you want to look elsewhere you are looking for a Taylor FAS-DPD K-2006 kit -- do NOT get a K2005! The lowest prices I've heard of are $47 plus shipping; typical low price is about $53 + shipping. It is VERY rare to be able to buy one locally.

2. Post the exact info on your pump and filter -- there's a high chance your pump is significantly too big for your filter, and besides wasting electricity, this causes filtration problems.

3. Let us know (add to your signature) any other equipment you have: SWCG, heater, spa, etc.

4. Tell us EVERYTHING you are using to treat your pool water.

There's a fair chance that you can strip the scale into the pool water . . . if you can raise your water level a bit. But setting that up requires exact knowledge of what's in your pool, and what equipment you have.

[MountainStone]

Thanx even more, Doc. I'll order the test kit today and get some actionable info as soon as I can, then return for your advice on my scale.

I was actually gonna start a new thread about the size of my equipment. Even though I know nothing about the subject, from my reading I have gleaned that my pump is probably twice the capacity necessary. The info I can discern from the data plates is as follows:

Pump housing: Sta Rite 'Model' MPRA6F-148L 'Code' 1C04T

Filter Housing: STA-RITE "POSI-CLEAR" CARTRIDGE FILTER PXC150

Motor: A.O.Smith
Total HP = 1.65
USQ1152
THERMALLY PROTECTED CET-50-ABM
MOTOR MOD: C48L2PA105C5
VOLTS: 115/230
AMPS: <blank>
RPM: 3450
MAX LOAD AMPS: 19.2/9.6
INSUL CLASS: B
AMB: 52 C
TYPE: UAC
HP: 1-1/2
PH: 1
CODE: J
FR: 48Y
HZ: 60
SF: 1.1
TIME RATING: CONT.

I have photos of the data plates if that would help. The motor was replaced by the seller of this house as part of the purchase agreement (motor was missing when we toured the house). I replaced the very old PXC150 cartridge filter last week with a new PXC175 cartridge filter, as that was the size/model cross-referenced when I looked up replacements online.

I have nothing else to add to my signature as I have no other features installed on my pool; no SWCG, no spa, no heater, no make-up water connection, no water features. Is there some way to indicate the lack of features in my sig? My plumbing is staggeringly simple: One skimmer, pump, filter, return to two eyeball inlets. I don't even have a way to bypass the filter. All visible plumbing is 2". The pump sits on grade, about 12" above the surface of the pool water. The pump is 15' from the skimmer, and the longest return line is probably about 50' if they ran it the longest route. Startup pressure with the new filter was 15 psi. As you may imagine, flow from the 2 inlets is very strong.

[MountainStone]

My recommended Taylor kit was delivered yesterday and today I tested my fill water and pool water:
Fill water:
FC = 1.2 ppm
CC = .2 ppm
pH = 7.6
TA = 140 ppm
CH = 270 ppm

Pool water:
FC = 4.2 ppm
CC = .2 ppm
pH = 7.8 (acid demand test yielded 1 drop to bring to 7.6)
TA = 180 ppm
CH = 600 ppm (tested this 4 times, once at 25ml and 3 times at 10ml)
CYA = 90 ppm

I listed my equipment specs in the post immediately above. For chemicals, I am using trichlor tabs in a floater and dry acid to lower pH. I was sold a Leslie's product called 'Scale Free plus' to combat my significant mineral scale. I have added one dose of that, though I dunno what it is since it does not state the contents on the bottle.

I appreciate any advice you care to give!