Stain and scale in a fiberglass pool

[kelemvor]

I'm sure one of the other contributors here will chime in with better information. But I'll give it a go since you've waited a few days already.

HEDP (Jack's Magic Pink), CuLator, and the ascorbic acid treatments are for dealing with metals. Do you have both metal and scaling issues? If not, then you should stop adding these things. The HEDP might be partly to blame for your cloudy water.

With a CH of 40, your calcium would be low for a gunite/concrete pool. It doesn't matter for fiberglass, and isn't particularly high in any event. I would leave your calcium level alone. You can remove scale with a little elbow grease and by lowering your pH to about 7. Don't go below 7, that is acidic and could damage your pool.

You posted two sets of numbers, there. On the second set the CYA level is significantly lower than the first. Did you replace a large volume of water (including rain and overspill)? If not, you should redo the CYA test. 90 is a good number for your SWCG (manufacturer recommends 80), 45 is not. Since CYA is hard to remove once it's in your water you want to be sure that the 45 reading is accurate before you add any CYA.

You have a SWCG and reported you were at 0FC and 0CC both the other day. Something's not working right with your SWCG. I use the same unit, you should be targeting 3200ppm salt for proper operation. Since you've had scaling issues, you may want to go ahead and do an acid wash on the cell (instructions are in the swcg manual). Until you get the SWCG working correctly, you should be adding chlorine as often as possible to keep your chlorine level appropriate for your CYA content. Since the CYA level in your pool is in question, I'd target the higher of the two numbers (90ppm cya) and dose chlorine up to 6ppm. If you're using chlorox 6% bleach, that's 112oz. In Florida there are a couple pool stores that will sell liquid chlorine cheaper than bleach goes for at the grocery. Adjust the dosage appropriately; for example "pinch a penny" sells 11.5% liquid chlorine. You'd only need to add 59oz of that stuff.

Don't use cal-hypo since you don't need the calcium.

http://cdn.bluehaven.com/downloads/AL723_manual.pdf This is the manual for the aqua rite swcg.

http://poolsolutions.com/gd/poolsolu...try-guide.html This is the poolsolutions guide to basic pool chemistry. It's written in a fairly easy to understand format, and I recommend you spend a few minutes reading it.

[Poolrn]

Thanks for the feedback Kelemvor. The SWCG is working ok, I had it turned off to bring the CL to zero. Was using polyquat every 3 days per the instructions. No issues with algae bloom. I have the SWCG back on line now, slowly bringing the % up without going to hi on the CL. Using bleach each evening to adjust the CL to 5 currently.

Yes the CYA did change a large amount due to vacuuming overboard to pick up the debris on the bottom. My current process to vacuum overboard is to turn off the SWCG, remove the T-cell unit and cartridge filter and turn the pump back on. That 2 inch pipe pulls a lot of water out. I have checked it twice and its still at 45. My goal there is to raise it 90. Iam waiting till the cloudiness issue is gone as I to clean the cartridge filter daily and am under the impression that powdered CYA can take some days to dissolve and its not good to clean the filter for say a week after adding the CYA. correct? At present the cloudy issue is about resolved perhaps a day or two and I can add the CYA.

I am fighting metal stain (lifted with vit C) and scale (scraped off scale bubbles with vinegar). Both developed over many seasons due to pool store advice. I had just lived with it for the past few years as I learned thru trial & error that the pool store doesnt have a cure in a bottle. Then I found this web site which was saying things that I had come to believe but couldnt find any proof. Such as CH is not that important in a fiberglass pool. My thought was isnt my fiberglass pool a reverse boat? No one I knows worries about their boats gelcoat in either fresh or salt water from a CH point of view.

It sounds like from your comment, reading in the forum and pool solutions website that my goals should be to keep the pH around 7.0 to 7.2, brush often, keep the maintenance dose of HEDP in the pool (per HEDP container instructions), keep CuLater packet in the skimmer, and the scale should slowly come off the walls. Does that sound about right?

I appreciate your comments, thanks.

[Poolrn]

Update on the pool. Its been a few weeks now and progress is going good, considering it took me years to mess it up! Im still working with removal of scale and stain. Ive kept the pH around 7.0 to 7.2 for the last few weeks, CH 40-50, TA 90-100 CL based on Bens Best Guess Guide and Culator in the skimmer/ w a sock, and some HEDP in the water.

The scale feels thinner with my fingernail. There is usually a small amount of whitish sediments that settle out over night that I vacuum up. The Culator is turning a tan yellow color indicating that it is removing iron from the water. The water continues to be a little white cloudy. The bottom is readily visible. I believe this to be the action of the HEDP, pH slowly removing the calcium scale.

I did learn a lesson regarding the Culator. I originally had one in the skimmer. Early in this process I added some borax to the skimmer forgetting that the Culator was under the sock. I believe that dose of Borax inactivated that Culator. A couple of days later I realized my mistake so I added the second Culator to the skimmer leaving them both in place. It is obvious now that first Culator didnt absorb anything cause the second is clearly turning tan/yellow. I'll send a picture of both to poolforum@gmail.com

Thanks again