Remove limestone on the sides of the fiber pool

[FIFFI]

(Admin note: Poster is in Denmark & doesn't have access to US methods and chems!)

it a in ground pool from 1974. 38000liters / 10.000gallons with sand filter with 125kg sand in and a 1kw pump.
The pool havn't been used for 2 years before wee bought the house.
on the sides there is a lot of lime stone, its all white.
the pool is closed down for the winter now.

kasper

[PoolDoc]

By "fiber pool" do you mean "fiberglass pool with a gelcoat finish"?

It's possible to remove calcium carbonate scale (CaCO3) from a fiberglass pool by lowering the pH to 6.0 - 6.4, and lowering the carbonate alkalinity to less than 80 ppm, and then holding those levels for an extended period. BUT . . . in order to do so, you need accurate testing capability and you need access to muriatic acid (~30% solution of HCl). If you were in the US or Canada, I could tell you where to go, and what to buy.

But in Denmark? Not so much.

Lovibond and Palintest products are available in various European countries, but the cost for the capability is 3 - 4x what it is here, and availability is spotty.

[FIFFI]

Hi

Yes I mean a fiberclass pool with gelcoat.
in Denmark muriatic 30% is normal to use. so that isn't a problem.
the problem is to test if the water has a ph on 6,0 to 6,4.
and alkalinity I test with strips. ( isn't that ok )


Kasper

[PoolDoc]

Strips are rather inaccurate. However, the pH and alkalinity results are easier to read with reasonable accuracy than the stabilizer (cyanuric acid) results.

The problem is that the range on the pH scale isn't going to reach 6.0, and the discrimination on the alkalinity test is usually too poor to allow you to distinguish 30 ppm TA from 80 ppm TA. But getting the TA below 100 ppm is more important than keeping it above 30 ppm.

But you must NOT allow the pH to get too low. 6.0 is a somewhat arbitrary figure, but pH = 4.0 is likely to damage your pool. Chinese made cheap pH meters are available in the USA; you may be able to find them in Denmark. Hanna Instruments is selling cheap Chinese made pH meters all over the world: http://www.hannainst.com/usa/about.cfm . You may be able to find a source you can use. You MUST purchase pH buffer solutions for calibration, as well. PH meters can NOT be trusted at ALL if they are not calibrated.

Good luck.