Question About The Pucks And Ph.

[Bugman1400]

I use the pucks and my pH drops. I used to fight this by using a fountain, but this also cools the water too much. Is it possible to drill a small hole and put a small check valve on the suction of the pump to aerate the water? Would this work to elevate the pH?

[chem geek]

You could increase the carbon dioxide outgassing by having the Total Alkalinity (TA) be higher. With a higher TA you may need a lower Calcium Hardness (CH) to not have the saturation index get too high though your risk of scaling is low since the pH will tend to stay low.

You do realize that your Cyanuric Acid (CYA) level is probably climbing quickly due to continued use of Trichlor pucks/tabs. For every 10 ppm Free Chlorine (FC), it also increases CYA by 6 ppm. So even with a low 1 ppm FC per day chlorine usage, the CYA will increase by over 100 ppm in 6 months if there is no water dilution.

[waterbear]

As chem geek said, the easiest way to keep the pH from dropping when using trichlor is to run a higher TA. What is your current TA. The accepted range for TA when using stabilized chlorine sources (trichor and dichlor) is 100-120 ppm but higher is not a problem if needed to help keep the pH from crashing. However, as pointed out above, you might need to try and lower the CH if it is high so you do not develop scaling conditions, which can occur if the pH rises too high.

Where do you normally run your pH?

A full set of test results would give us a lot more informatin so we could better advise you.

[quantumchromodynamics]

Is it possible to drill a small hole and put a small check valve on the suction of the pump to aerate the water? Would this work to elevate the pH?

No, you do not want to introduce air, or any other gas, into the suction of a pump.

My recommendation would be for you to significantly reduce your reliance on tabs. I recommend that you begin to use liquid chlorine as your primary source of chlorine.

[Bugman1400]

Well crap.......so you're saying that the pucks also kill (drop) the T/A. I did not know this. Well, you're right......the Taylor kit indicates that my T/A was between 70-80. I guess I'll stick to the liquid chlorine. Is there a good way to boost the T/A? Also, do they sell the pucks without all the CYA? Also, does a high CYA cause any swimming discomfort like burning eyes, etc. or is it just detrimental to the T/A?

One more thing...I have a liner so I'm guessing that CH is not a problem even if its high?

[waterbear]

Well crap.......so you're saying that the pucks also kill (drop) the T/A. I did not know this. Well, you're right......the Taylor kit indicates that my T/A was between 70-80. I guess I'll stick to the liquid chlorine. Is there a good way to boost the T/A?

Baking soda (aliases: sodium bicarbonate, sodium hydrogen carbonate) is used to raise TA.Yep, the stuff from Arm and Hammer! If you want to pay a premium price for the same thing you can buy it at the pool store as "total alkalinity increaser".

Also, do they sell the pucks without all the CYA?

No and here is why. For an erosion feeder to work properly the chlorine must be very slow dissolving There is only one very slow dissolving chlorine chemical for pool use called trichlor. All other solid forms of chlorine dissolve much faster and are not really suitable for erosion feeders. Trichlor is a chlorinated isocyanurate, a chemical made from cyanuric acid (CYA) and chlorine. It is a CYA molecule that has 3 chlorines attached to it, hence trichlor. Once the chlorine is used up the CYA stays behind.

Also, does a high CYA cause any swimming discomfort like burning eyes, etc. or is it just detrimental to the T/A?

It causes no discomfort and it does not have any impact on the TA.

What is impacting the TA is twofold:

1)trichlor has a very low pH of around 2 so it is like you are always adding acid to your pool (in effect you are)

2)when chloirne sanitizes and is consumed the reaction is also acidic so you are adding even more acid

With unstabilized chlorine sources like beach and cal hypo they also have the acidic reaction when they sanitize but they are alkaline so the net effect of using them is basically pH neutral.

Eye discomfort is usually from too low a pH or combined chlorine present in the water.

One more thing...I have a liner so I'm guessing that CH is not a problem even if its high?

Low CH is not a problem with a liner. High CH is a problem for ANY pool and can lead to scaling and cloudy water under the proper condtions.

[chem geek]

If you switch to using chlorinating liquid or bleach, then I'd leave the TA where it is now at 70-80 ppm since that is more likely to give you a more stable pH when using hypochlorite sources of chlorine.

CYA is not just acidic and causing lower pH and TA, but the increasing CYA (from continued use of Trichlor, for example) makes the chlorine less effective unless you proportionately raise the FC level. So at some point with a higher CYA and low FC algae can grow faster than chlorine can kill it which initially appears as higher chlorine demand but then has the water turn dull, then cloudy, and eventually a full-fledged algae bloom.