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!

[PoolDoc]

OK. You've got several options here.

1. We can get the water in shape to OPERATE, with no new scale, pretty easily. But, with that high calcium level, it's going to be hard to get it into a calcium-removing state. If want to just operate the pool, and let the scale go, you can lower the pH and aerate, till your TA is much lower, and you'll be fine.

2. To LOWER the calcium, you have two options. The first is simply to drain and refill. But, with a fiberglass pool, if there's ANY water in the ground, your pool can FLOAT out of the ground, destroying it. If you're on hillside, and the weather hasn't been soggy, you are probably fine. If you are in a flat or low area . . . be VERY careful! (Since you're in Las Vegas . . . it may not be an issue!)

3. Your second option is more complicated, but won't waste so much water. You can do a 'lime-softening' process, by adding a bunch of sodium carbonate, till the calcium precipitates, and then vacuum and filter it out. Doing this, you can end up with quite low calcium -- lower than the fill water -- and that will help you strip the scale. Here's the process:

+ raise your water level to the max -- if it's safe, raise it to spill over.
+ remove your cartridge from your filter
+ add a dose of PAC floccing agent
+ follow it with sodium carbonate till your pH > 10.0
+ mix, turn your pump off, and let it settle.
+ vacuum the floc to waste. (you may have to add T valve to enable this)
+ replace the cartridge filter, turn the pump back on
+ add muriatic acid till your pH is ~ 7.0, and begin aerating
+ use acid + aeration to strip carbonate alkalinity till your TA > 80 ppm
+ hold your pH at 7.0 - 7.2 till the scale is gone; try to keep the water level ABOVE the scale.

The last option is by far your best choice for removing scale and stains. And, it's not as much work as it sounds, but you will have to be careful to follow the process. To do it, you'll need several items;

+ Poly aluminum chloride floc
+ Wide range pH test strips
+ Washing soda from Walmart (yellow box, maybe 8 boxes?)
+ Muriatic acid from Lowes (gallons, maybe 4 gallons)
+ HEDP for post treatment

You can get the washing soda (soda ash, pH up) and muriatic acid locally and cheaply; I'll need to help you get the exact item on the other three products, if you're interested.

Given your fill water's condition, and the high evaporative rates, learning to do this might be worthwhile. You *should* be able to get lower calcium and alkalinity levels than you have in your fill water. I'm guessing you might need to do it every other year, to avoid scale, and I'm guessing water in Las Vegas costs enough so that this should be cheaper than draining and refilling. (I'm guessing total cost may be around ~$100.)

[MountainStone]

Wow, thanks for the in-depth info Doc. To help me choose a course of action, can you answer a couple of noob questions?

1. What is the disadvantage of high calcium hardness, other than the scaling on my fiberglass? You say I can just lower my TA and be fine; does that mean there are no adverse effects on my water treatment regimen or my pool equipment from a high (and increasing) calcium hardness?

2. It would cost me roughly $60 in water to drain and refill the pool, but I hate wasting water and I have no knowledge of the local water table so would be VERY hesitant to drain this fiberglass pool.

3. Your second option for lowering calcium hardness sounds pretty intense but I'm sure I could do it (I have a T-valve that has a capped threaded stub). How long do you think the pool would be out of operation? It is almost warm enough to swim here and we are looking forward to getting in our new pool for the first time in the next couple of weeks.

I really can't say 'thank you' enough times!

[PoolDoc]

1. Yes, you can do just that . . . as long as the scale doesn't bother you AND you don't get a heater or an SWCG. High calcium can cause problems with either one.

2. If you're in Las Vegas, you are probably pretty safe draining the pool. I'm assuming you on dry sandy soil? (I don't know; sorry, but Las Vegas has always been at the bottom of the list of places I'd like to go, just below Newark, NJ ;) ) My only concern is that you'll STILL have high calcium, and have a hard time removing the scale.

3. You'd want to allow 2 weeks. I think it would be less, but I don't know for sure.

If you're ready to swim, and the scale isn't a problem, why don't you just lower the TA, and then make a decision this fall about whether you want to go further? This page will tell you how to do it: http://www.poolsolutions.com/gd/lowering-swimming-pool-alkalinity-step-by-step.html

[MountainStone]

Doc,

I think I will take your advice and lower the TA of the pool for now without worrying about the high calcium and the scale. I just dropped my pH to 6.8 and pointed my inlets at the surface to impart some 'ruffling.' I think I'll pick up a couple of the little fountains that attach to the inlets to better aerate, as I will likely also need them to help lower water temps this summer.

I'll attack the calcium buildup at a later date. As you say, the soil here in the Las Vegas valley is sandy and full of caliche. The grade falls away from my neighborhood, so my little 5' deep pool is likely above the water table. I think all our drinking water comes from Lake Mead; there may not even BE a water table. Draining/refilling may be an option at the end of summer if I don't feel adventurous enough to try your method of precipitating it out.

Thanks for all the help!

[PoolDoc]

there may not even BE a water table

that's what I suspect!