Total Alkalinity Probs

[JJ]

I am struggling with a vicious cycle of Total Alkalinity (TA) and ph regulation.

I have an auto doser for ph levels.

I understand that the Total Alkalinity is a buffer to stop major movement in ph levels.

My TA is low, so I add several kg of bicarb of soda, this causes the ph level to rise, so my ph doser adds more acid, which in turn lowers the TA.

I have just switched off my ph doser to see if I can get the TA right first.

Should I have done this first? I have read that you must get the TA correct before adjusting the ph.

Anyone else had similar problems.

On the positive side the pool is crystal clear and sparkling. That could be due to my rigid pool maintainence regime or it might be helped by the fact that a few weeks ago I had Poolguy change my sand to zeolite/zelbrite and that has made a big difference, also I only need to backwash every 3-4 weeks which cuts down on water useage.

 

 

[Jonzjob]

My TA was about close to 0 not so long back and I had to put a boat load of bicarb in the pool. I just turned of the PH feed from my auto system and let the bicarb do it's job. The TA is now correct, the PH settled down OK and apart from a problem with the auto feed valves, which is being sorted now I hope (?), all has been well. Don't put too much bicarb into the pool at once. I can't remember the overload amount off hand, but I put a couple of pounds disolved in a bucket of water followed by another similar and left it for 24 hours with the pump running and checked it to see if any more was needed.

If the TA was very low, why? Was it due to a lot of rain? If so then have a look at the cynuric acid level too (stabiliser) because if that is low then you will be using a lot of javel. It should be about 50 ppm. Dichlor (shock chlor) will bring it up to level if it is low. But it will also shock your pool too!

[JJ]

Jonzjob,

Many thanks for that. How long did you leave your auto ph doser off for?

Cheers.

[Jonzjob]

This all happened at the beginning of the winter just gone. I am a bit vague, you get like that at my age [:(](?), but if I remember correctly I left it until the PH had come back down to 7.2 ish. A day or 2 if I remember correctly?

I keep a diary for the pool, most times anyway! But I failed to put that detail in it... It was just after I had the TA correct that I put the dichlor in and the auto reading went up to 800 mv, I also tested it with my coolpool tested and all that read was 'Hi' and it stayed very high all through the winter until the water temp started got get higher. Now apart from some debris in the bottom of the pool all is well. That will get vacuumed out in the near future.

Sorry I can't be more helpful on that..

[Poolguy]

Hi Jim

Thanks to John for doing most of work for me.... ta

Adding to what he has said; Jim in your pool a reading of below 20ppm

in TA (total Alkylinity) will need about 10-12 kg of food grade Bi card

to bring it to the min levels of 80-100ppm9 add about 2 kg at a time,

mix and circulate). This will naturally send the pH through the roof as

they are related but not the same. Your pH moins controller will then

work away to get it down again to a nice 7.2 at which time as you have

adequate 'buffer' (TA) in your water that it should stick there nicely

- no pH bounce (up, down round about, give a dog a bone....!)

There are several reasons that you might have the TA dropping:

• That you have introduced a significant portion of freash water either by rain or by the hose.
• That you have been dosing a significant amount of pH moins for a while.
• That the calcium hardness is also too high.

Either way its a good idea to be on top of that one about once a month during the hign use period of the year.

It will save you money in the long run and avoid the initial pain of pH

bounce. As bi card is so cheap to store in bulk, it makes sence to have

a sac around just to make those adjustments and it keeps for ages (not

like chlore).

Let me know if you need any more specific help

Andrew

[JJ]

Andrew,

Thanks for that, I have switched of the auto ph doser for the moment, added enough bicarb to get my TA up to 140 which is a tad high.

The auto ph doser is saying ph at 7.6, but photmeter tester says 8.6.

I seem tro still be in that vicious cycle of adding bicarb, then acid etc etc.

I will see if turning on the ph doser works in getting the ph down.

Regards.

Pool is running very well otrherwise though.