I have a problem with a pool situated in the Cook Islands in the South Pacific.

The water here is VERY hard and reading the information here on TFP am aiming for a TA of 100 and pH of 7.5. There is a blocker in the pool to keep the CYA levels up and the FC is over 5.

Before achieving these levels, I had algae form. Shocking it with Chlorine got rid of most of it but I still had quite alot of staining on the bottom. This required draining the pool & acid washing it off. This worked ok, but now I have the pool refilled and I am getting alot of white 'dust' on the bottom of the pool. This happened before too.

Is it likely to be the calcium falling out of the water formiing a 'layer' over the pool not allowing the chlorine to work or could it be undissolved chlorine falling to the bottom. the pool is approx 45,000 litres (approx 1200 U.S gals) and on refilling I have put in 5 litres (1.3 U.S gals) of acid and 600 mls of chlorine over a day.

At the moment TA is 130 and pH is 7.6. There is alot of this white dust which rises when the pool is sweept.

Any ideas what is happening, and what I should be doing to improve the water quality and prevent algae from coming back.

That was a lot of acid. What was the pH to start?
Are you sure the pH test reagents?
When you drained the pool and did an acid wash, what strength Muriatic acid was used and how diluted?
How was it neutralized? Rinsed?

The situation you are describing sounds a lot like the condition of new plaster being brushed. This can happen with an acid wash that wasn't well rinsed/neutralized. Keep brushing towards the drain.

Scott

Welcome to TFP!

Can you post a full set of water test results?

I have been battling clouds of probable calcium in my pool for some time (old plaster, AA treatment in fall, and new to me but old Aquabot that scrubs the walls better than my other cleaners), and it is finally clearing up. I was so impatient. See this post.

http://www.troublefreepool.com/i-m-still-not-seeing-the-bottom-t18969.html

The post also has a YouTube of the floating "clouds". The advice from my "Favorite Most Trusted Pool Guy", when he installed my new pump and filter, was to let the filter clear the pool before doing anything (other than keeping water balanced of course). As you will see in the thread, I was advised to let the pool clear and then carefully manual vacuum the pool.

The pool seemed to reach a point, in past few days, where I could see the bottom drain, and now the clearing has accelerated drastically. I'm waiting a few more days before breaking out the manual vacuum.

gg=alice

I think you mean 12,000 us gal

Thanks for the replies. I will get a pool test done in the next hour or so and post it. Yes, pool size is 12,000 U.S gals. I scrubbed the pool floor with a Hydrochloric/water mix. 5:1 and had to really scrub hard to get the staining off. Small amounts of water was run into the pool floor and washed over the completed areas, but I didn't do a concerted rinse. I didnt do a ph test on this fill, but from the last fill ph was over 8.2 (top of the scale of the test kit) & TA close to 200. We have our own well on site. I will keep brushing towards the drain. Will a sand filter take out the calcium? Back soon with a test result.

Pool test: TA 160, pH 8.2 (top of test kit scale), FC 5 (top of test kit scale). The 4 in 1 test kit I have doesn't do cya test, but a test strip shows 30-50. The pool has an ionizer system. Copper level 0.5ppm. The water was quite cloudy yesterday but is clearing today.The drain is now visible (6ft deep). White powder visible on the bottom.

Be careful with the high PH and copper that high. You may want to use some sequesterant for the copper.
(note: I don't like Ionizer systems). Is it safe to assume you are still adding acid (get that PH down! ...

The sand may take longer to clear the dust but it should. You could try a little DE in the filter, read about that in Pool School.

As for the "top of the scale", consider getting one of the recommended test kits - strips are very unreliable, especially for CYA levels. You can read about the two kits we recommend in Pool School. The FAS-DPD chlorine test reads chlorine levels up to 50ppm, which is extremely helpful.

Thanks for the good info. Will add acid and keep vacuuming. Can these test kits be purchased thru TFP?

duraleigh sells the kits at TFTestKits.Net

These kits are the best bang for the buck and the customer service is A1. Most of us have a link to his site in our sig.

Ok, thank you.

Since refilling the pool 6 days ago, I have put in a total of 8 litres of Hydrachloric acid. 4 litres on initial fill (TA 160 pH 8.5 the next day) & 1 litre per day (except one). On the 2nd day TA was down to 130 pH 7.5. The TA & pH have remained the same each day and today despite the 1 litre added last night the TA is still 130 & pH 7.4. Over the six days I have put 1.4kgs (3.1 lbs) of chlorine in. FC is 3. CYA (shows on a strip) 30-50. The water is also a little bit cloudy, although I can see the bottom ok. Any ideas on why the TA isn't coming down & why the water is still cloudy?

It takes quite a bit of acid to lower the TA level, and the test rounds to the nearest multiple of 10. Your TA came down each time you added acid, but the TA didn't change enough to get your down to the next lower TA reading. Keep at it and the TA will continue to come down.

There are a great many possible reasons for cloudy water. Algae is the most common cause, but there are many many others. Aside from the possibility that you are getting algae, we need to see a complete set of water test results to make any kind of guess at the cause.