Salt Water Test Strips

[severn]

There has been a few enquiries re testing the salt level in a pool

We now stock salt water test strips - 10 strips per "can"

They can measure up to 7,000 ppm

Details @ pwpoolthailand.com

[PoolDoctor]

Test strips are not needed, there is a low salt warning light on every chlorinator. Simply add enough salt so that the light goes out. Any more than that is too much, and the water will taste salty.

[severn]

Beg to differ.

The chlorinators are not that sophisticated,they provide an indication which is fine when they are new but they will become less accurate thru use / corrosion.

Each manufacturer has different salt ppm guidelines depending on temperature.

eg Hayward 3,200ppm

Zodiac 4-5000ppm

Watermaid 6-7000ppm

Replacement Chlorinator circa 20,000 Bht .. Test Strips 300Bht

There is no right or wrong,some people like to know what's going on .. others do not.

[fdimike]

I was told pretty much the same thing by the Poolrite (Australia) CEO. Don't rely on the indicator in the chlorinator. You really need to test the water for sodium chloride level to avoid damage to the cell. It's easily done with a salt water hydrometer available at most any aquarium shop here in Thailand selling salt water fish and associated gear.

[in2fridge]

ahem...

Aquarium salt water hydrometers are not really suitable for a pool,they are calibrated to measure the far higher levels of a salt as sea water aquarium .. they also measure in specific gravtity.

Swimming pool in the far more detailed ppm

Recomended Specific Gravity for an aquarium is 1.012 = 15,900ppm

to 1.024 = 31,900ppm

yes the scale starts @ Sp G 1.0 = 0ppm but because the scale is more coarse, moves in increments of .010 = 13,300 ppm

so really the best it can tell is if there is any salt content in your pool OR that it is dramatically over the top.

They also are usually designed to function best 23%-29% C

2,000 ppm = 1.002 Sp G

6,000ppm = 1.005 Sp G

So it will work, but not very well ...and .. if one size fits all why do manufacturers make/ sell seperate aquarium and pool/spa test strips and hydrometers ?

[fdimike]

In

I'll admit to not being a chemist. However, I am going to disagree with you regarding the use of a salt water aquarium hydrometer to test pool water. The unit I purchased measures salt content below the amount required by my chlorinators. Measuring salt content of aquarium water is no different from measuring sea water or the salt water in your pool or brackish water or for that matter the salt water you may use to rinse out your throat with when you have a cold. The purpose of a salt water hydrometer is to measure the amount of dissolved salt in the water sample. It is not rocket science by any stretch of the imagination.

I would be happy to apoligize if you can show me that I'm incorrect.

[in2fridge]

I think we will have to agree to dis agree !

My point is ..Yes a marine will work,BUT a specific pool/spa test strip or hydrometer will do a far better more accurate job as it scaled for 0 - 7,000ppm.

A typical marine version scale is 0 - 1.070 Sp G

that translates to 0 - 91,400 ppm

This means the required pool salt levels are barely registering on the bottom of the marine scale...

I personally would rather use a medium specifically designed for my pool/expensive chlorinator system . ....to me 300Bht for 20 strips used probably 1 - 2 times a month is far preferable....

I am not disputing a marine hydrometer doesn't work - just not as well as pool specific.

Edited July 26, 2011 by in2fridge