Can't Get My Ph Up, Added A Lot Of Soda Ash Already

[steve haigh]

hi, can anyone help?

i have recently filled my pool (concrete inground, 30,000 liters, tiled) and i've added a lot, perhaps about 15kg of soda ash but i can't get the ph to budge, it sits at 6.8. i should mention that the bag of soda ash got a bit wet a few days ago and turned into a solid block. i have to knock it out with a hammer and desolve it for an hour before use, but i figure it should still work right?

any ideas why i can't get the ph up? i know my water supply is acidic, i know i need to add alkali, but how much?

also, i live in Thailand in the boonies and don;t have access to fancy pool supplies, just soda ash, acid and chlorine.

[D0TC]

#1 - make sure the kit you are using to test is still good!!

#2 If your pH is too low, you'll only register as the lowest the kit is good for! - I think that your pH is well below 6.8 and that's as far as your tester will measure - keep 'pounding' away with the soda ash ( add 2 lbs at a time, wait 2 hours with the system running and check it again)

[steve haigh]

#1 - make sure the kit you are using to test is still good!!

#2 If your pH is too low, you'll only register as the lowest the kit is good for! - I think that your pH is well below 6.8 and that's as far as your tester will measure - keep 'pounding' away with the soda ash ( add 2 lbs at a time, wait 2 hours with the system running and check it again)

the kit is new, Hayward, and yes, i suspect the ph may be lower than the lowest reading.

i added more soda ash today and now the whole thing turned milky white with white particles floating around, looks like undesolved soda ash, and the filter doesn't remove it!

i love pool chemistry! aaarrrrggghhh!!!

[ANG]

Your PH is controlled by the Total alkalinity. If the alkalinity is low it will drag down the PH with it. Try and get the alkalinity to 120ppm and you will see the ph rise with it.

[steve haigh]

i found this post on another pool forum http://x.havuz.org/viewtopic.php?t=641

the poster said the answer is to airrate the water to get the trapped CO2 out thus reducing TA which was acting as a buffer. (by the way, i can't measure TA, i don't have a test kit for it, i just assume it was high because i was unable to change ph)

so i got a couple of pieces of 1 1/4" pvc pipe, bent them about 45degress and flattened the end to make a water spray. then i pushed the pipe into the returns with the ends above the water line and used string to hold them up to create 2 nice waterfalls. i ran the pump for about 8 hours yesterday and let it sit overnight.

this morning, the pool is clear and the ph is spot on; i assume all that floating soda ash desolved and raised ph.

i wonder if constantly airrateing the pool is generally a good thing or if i so go back to the standard setup? its certainly a cheap and environmentally better solution than adding a ton of chemicals

steve

[chem geek]

Steve,

I was the one that wrote about using either 20 Mule Team Borax or aerating the water to make the pH rise, but the aeration only works well if the Total Alkalinity (TA) is already high and in that poster's case they wanted the pH to rise without further increasing the TA. You didn't mention your TA level (you say you don't have a test kit for that) -- if the TA is low than Soda Ash is indeed the better approach to raising both pH and TA, but if the TA is already high then aeration is better. Are you able to get a good test kit? If you are using test strips, then your results may not be accurate. At least for the pH test, see if you can get a standard test that uses phenol red and compares color to a comparator with yellow being acidic and red/purple being alkaline (7.5 is light orange).

Richard

[steve haigh]

Steve,

I was the one that wrote about using either 20 Mule Team Borax or aerating the water to make the pH rise, but the aeration only works well if the Total Alkalinity (TA) is already high and in that poster's case they wanted the pH to rise without further increasing the TA. You didn't mention your TA level (you say you don't have a test kit for that) -- if the TA is low than Soda Ash is indeed the better approach to raising both pH and TA, but if the TA is already high then aeration is better. Are you able to get a good test kit? If you are using test strips, then your results may not be accurate. At least for the pH test, see if you can get a standard test that uses phenol red and compares color to a comparator with yellow being acidic and red/purple being alkaline (7.5 is light orange).

Richard

i have the red phenol drops for testing ph and the yellow one for chlorine in the heyward kit. but that's all it tests, ph and chlorine. i just ordered some Aquacheck test strips because they also test TA and a other things, but they havn;t arrived from the US yet.

anyhow, my pool looks great now. i kept one of the waterfall spout things in place because i like the sound of the falling water and the water just looks healthier with the bubbles in, don;t know if it really makes a difference at this point.

thanks for all the help.