Aerating Pool to raise PH - Hiblow XP40

[Denniswiseman]

Looks good

[Phil.c]

Here's an update.
Yesturday morning at 7:30 the PH was 6.8 and ALk 54, aeration was turned on then and until 10:30pm. (Pump speed 1200 and on for the same amount of time) This morning at 7:30 the readings are PH 7.0 and ALK 68?

[Phil.c]

Well, to be honest, I am lost for words....I have been aerating for three days to raise just PH and with the pump running for around fourteen hours a day, here are my figures including this mornings:-

Day 1 PH 6.8 ALK 54
Day 2 PH 7.0 ALK 68
Day 3 PH 7.2 ALK 128

I think all references to aeration only raising PH should be changed to, aeration raises PH and also ALK but ALK being raised at a higher rate!

A much cheaper option for me would have been, not to spend £220 on the pump and save three days of electricity, Lower PH & ALK with PH decreaser (which I did) then slowly raise the PH!

[Teapot1]

Using acid to lower your pH and then adding pH increaser will put you right back where you start.
Yes reducing ALK is a process and it doesnt happen all that quickly but it does happen. You, like myself are starting from a high ALK point.
Yes as the pH increases you do see an increase in ALK figure but less so each time. Its one of the reasons I like to keep my treated water and not just flush/backwash it away knowing the top up will put me back to higher ALK again. I am still experimenting with air scour to assist backwashing and reduce waste water. its a lot of water for a little bit of dirt in my book! I also use fresh tap water to assist with backwash rather than treated pool water but my pool is in France where water is supplied around 7 bar, not the pathetic trickle we have in the UK. Next re model of my pool will hopefully include a 3000 ltr water storage tank for topping up with softer rain water.

[Phil.c]

I'm sure I read on this forum that aerating increases PH but not Alk, as you can see with my figures my PH has risen by 0.2 a day but my Alk is gone sky high again, my PH is right at the bottom of the scale but raising it even a touch higher would also raise the ALK with this aeration method which would bring me back to where I started.
I had this high ALK problem a couple of years ago and was told here, to lower the PH/Alk then slowly higher the PH.

If I lower the PH again to lower ALK and then use aeration again, I'm only doing what I have just done because ALK will just rise again and faster than the PH???

[Phil.c]

Here's something interesting, with looking at my ALK figures, that big jump from 68 to 128 got me thinking, so I've just done another test with my ColorQ (LaMotte) kit only to find that the new ALK figure is 78 not 128 ??? Why the different figures???

[Teapot1]

To a degree yes, but you should see a decrease in the ALK compared to the previous times for the exact same pH reading. Life would be very much easier if aeration did not increase the reading of ALK and just the pH but the two are linked. As pH increases the ALK increases but using aeration it gets less of an increase each time, as ALK reduces it takes longer to increase the pH. When I did this in my workshop I could not get the pH to increase at all after 48 hours of aeration with an ALK of 40ppm.

[Teapot1]

Are the tablets in date? Time and water temperature can also affect test results.

[Phil.c]

Tabs in date but will need more shortly, water temperature and time the same.

[Phil.c]

The reading this morning, PH 7.4 ALK 92, time to stop aerating otherwise ALK with be back to square one.

[Teapot1]

I would continue to aerate up to 7.9-8.0 pH then acid dose to reduce pH once more. Too smaller swing to be doing much good otherwise.

[Phil.c]

Will do.

[Denniswiseman]

If you get another two airstones it will speedup the pH rise

[Phil.c]

Just did that, there's a manifold that came with the pump so it just means adding two extra stones to it and blocking off the remaining ports.

[Phil.c]

Just another update, I have two extra stones but I'm still waiting for the T pieces, I couldn't use the manifold that came with the pump because the connections are two small. I agree with Dennis that with four stones the PH would be raised faster.

So, This is the fifth day of aeration and the latest figures are :- PH 7.6 ALK 114, to do as Teapot suggested, I would need to aerate for another two days to get the PH to 7.9-8.00 however, the ALK then would read around 140, if I then lower the PH the ALK will be at the top of the scale. I'm no pool expert but it seems to me that the aeration method is not ideal for this situation, I have in the past, lowered PH to lower ALK then slowly raised PH to get ALK right?

Probably better to stop aerating now with the figures I have?