Trichlor Tablets for Separate Water Feature

AJB1234

Gold Supporter
Dec 5, 2015
125
Newport Beach, CA
Hi TFP,

I have a water feature that is separate from my pool but has a Hayward pool VS pump and filter. The PH is extremely difficult to balance and I'm assuming it's because of the following reasons:

*Large size of the waterfall causing aeration
*Evaporation of water and autofill consistently adding high Ph water.

I was planning to go with the stenner/timer for muriatic acid option but was recently given the idea to use Trichlor tabs in the puck feeder as this will lower ph(my main concern). I initially went away from this idea due to the potential consistent increase in CYA but if no one is swimming in the pool and not much chlorine is needed to prevent algae (lots of movement of water and shady area), maybe this is a better/easier option. Also, if i am correct that the autofill is adding a lot of water then that would bring down the CYA level and perhaps prevent it from getting too high.

If the Trichlor puck option is best, then how do I accurately manage the CYA and Ph when I'm not able to measure the dosage using the pool calc (which I love for adding MA and other chemicals).

Thanks for your help!

AJB
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,564
Northern NJ
Your autofill will not lower your CYA unless water is drained. Evaporation does not lower CYA.

Eventually the CYA will get to a level where the pucks can’t provide enough FC to keep algae away. You will need to do an occasional drain to keep CYA under control if you use trichlor pucks.
 

AJB1234

Gold Supporter
Dec 5, 2015
125
Newport Beach, CA
Thank you for your response. I didn't know that evaporation doesnt lower cya but wouldn't the addition of new water that has no cya lower the water that has cya?
I'm not really concerned about chlorine as the movement of the water prevents algae but am more concerned about proper ph balance (to keep csi in check and reduce chances for calcium build up).

Thanks again.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,405
Laughlin, NV
Movement of water does not prevent algae. Having the proper amount of FC for your CYA does.

CYA is a dissolved solid. It stays in the water in the vessel. You do not get rid of it through evaporation.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,564
Northern NJ
Thank you for your response. I didn't know that evaporation doesnt lower cya but wouldn't the addition of new water that has no cya lower the water that has cya?
With evaporation the CYA gets more concentrated in the remaining water The CYA PPM would increase. The new water then dilutes the water back to the original PPM. No CYA was lost.

I'm not really concerned about chlorine as the movement of the water prevents algae
Movement of the water may prevent the algae that is in the water for sticking to surfaces. The algae will grow in the water, consume FC, and create CC. Given enough time you may end up with a green swamp.
 

AJB1234

Gold Supporter
Dec 5, 2015
125
Newport Beach, CA
Thank you. I think I am ok with cya getting too high because draining and diluting the water shouldn't be too difficult since it's a fountain and not a pool. My main question is how do I keep ph #s in the target range by using trichlor pucks. Seems easy with acid since I just plug in the #s in the pool calc and I know how much to add. It definitely would be nice to go with the puck option vs stenner/MA option. Thank you for all your help!
 

Oly

Gold Supporter
Jun 28, 2017
1,170
Fresno, CA
You can use pool math by estimating gallons in your fountain then using the "Effects of adding chemicals" to estimate how much each puck lowers pH given that volume of water. Another factor you will have to consider will be the rate at which the puck dissolves and this will vary with the water temperature. You should be able to get in the ball park then confirm by testing the pH and FC over time. You can also estimate the expected rise of CYA over time with this calculator.
 

AJB1234

Gold Supporter
Dec 5, 2015
125
Newport Beach, CA
This is very helpful, thank you. Using the "effects of adding" on the android phone app under trichlor it only shows weights (grams, kg, oz, lbs). Should I determine what each puck weighs and then use that as the amount to add to the calculator?
 

proavia

LifeTime Supporter
TFP Guide
Feb 6, 2015
1,616
Chandler AZ
Usually, a 3" Trichlor tab weighs 8oz. You'll need to determine the volume of your separate, non-attached water feature and plug that data into PoolMath to get an accurrate result of how each tab will affect pH, FC, CYA.