Help Determining Ideal Chemical Levels For My Pools

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SuzakuTheKnight

0
Nov 19, 2013
17
Madison, AL
I'm currently managing two pools and a spa. I'm trying to figure out if I should make any adjustments to the standard ideal ranges to improve their water chemistry. Any feedback or suggestions are welcome. All pools are located in Madison, AL.

Chemicals In Use
Cal-Hypo Tabs (68%) (On CAT 2000 Auto-Feed for All Pools)
Cal-Hypo Granular (68%)
Muriatic Acid (31.45%) (On CAT 2000 Auto-Feed for All Pools)
Sodium Bicarbonate
Soda Ash
Sodium Thiosulfate

Main Pool
Volume: 55,000 gals
Depth: 3.5' to 4'
Type: Indoor Plaster (3 years old)
Temperature: 85 F
Filtration: 7 1/2 HP Pump w/ 3 Triton TR-140C Sand Filters

Last Chemical Check
FC: 3
CC: 0
pH: 7.4
Alk: 100
CH: 500
CYA: 0

Notes:This pool gives me hardly any issues. At these levels the water maintains great clarity, though not 100% (there are some extremely fine particles in the water). Should I be concerned with the high CH level? I don't notice any scaling.

Splash Pool
Volume: 6,360 gals
Depth: 0' to 2'
Type: Indoor Plaster (3 years old)
Temperature: 90 F
Filtration: 2 HP Pump w/ 1 Triton TR-140C Sand Filter

Last Chemical Check
FC: 3
CC: 0
pH: 7.4
Alk: 100
CH: 360
CYA: 0

Notes: This pool has water features that, when in operation, cause rapid aeration. Whenever the features are running, alkalinity and FC seem to drop somewhat rapidly. I believe the alkalinity decline is due to the aeration causing a pH rise and therefore causing the CAT controller to feed acid.

Spa
Volume: 1,250 gals
Depth: 3.5'
Type: Indoor Plaster (3 years old)
Temperature: 104 F
Filtration: ? HP Pump (label has worn off) w/ 1 Triton TR-140C Sand Filter

Last Chemical Check
FC: 3
CC: 0
pH: 7.4
Alk: 100
CH: 360
CYA: 0

Notes: The spa has hydrotherapy jets that cause a lot of aeration. Cannot seem to hold a stable alkalinity level throughout the day (probably the aeration -> pH rise -> acid feed situation again). I drain it weekly due to the high bather load it sees. Although the PSI on the filter never seems to increase, more than a week without draining the water causes the water become hazy despite good chemistry.

I've been targeting FC 3, pH 7.5, and Alk 100 for all of the pools so far. Wondering if these targets should be adjusted at all. All input welcome.
 
Well, you are doing several things we would not encourage but you seem to be doing just fine so I would be reluctant to suggest a change.

I am VERY curious about the Cal-hypo tabs....those are virtually never used in pools....do you have a pic of the label?
 
:wave: Welcome to TFP!!!

I would agree with Dave that nothing really jumps out a that bad. You seem to have a pretty good grasp on things like the TA dropping due to automation of the acid addition to counter the pH rise due to aeration ... that puts you leaps and bounds ahead of most first time posters ;)

Your CH could certainly start to be a problem as it continues to rise due to the apparent exclusive use of cal-hypo.

Are you prohibited due to regulations from using any stabilizer (CYA) in the water? If not, we generally suggest a level of 20-30ppm even for indoor pools, not for the protection of the FC from the sun, but for the massive buffering effect on the chlorine. You could make the water a LOT more gentle on people by maintaining the same 3ppm FC level, but having some CYA in the water.
Looking at this chart showing the active chlorine level: http://richardfalk.home.comcast.net/~ri ... l/HOCl.htm
For a CYA of 0 and a FC of 3ppm, the active HOCl is 1.45ppm
Raising the CYA up to 20ppm, the active HOCl drops to 0.067ppm .... that is over 21 time LESS harsh than currently, but still perfectly sanitary.
Of course, depends if you are allow to use it or not in your jurisdiction.
 
duraleigh said:
Well, you are doing several things we would not encourage but you seem to be doing just fine so I would be reluctant to suggest a change.

I am VERY curious about the Cal-hypo tabs....those are virtually never used in pools....do you have a pic of the label?
Click to expand...

I do, and I'll attach it below (It's not the full label, but I can get that tonight if needed). I've had to hit the ground running following what the last operator was doing. It's a non-profit organization, so any change that involves money has be be fought for. I'm completely open to changing how the pools are managed if I can present a valid argument to the upper management.

Edit: I'm also curious about their use... If I recall correctly, they have a high pH value. So not only are they raising the CH but the pH as well. We seem to burn through a lot of acid. If I can reduce the amount of acid we use per month, I would be very happy.

20130924_184935.jpg
 
jblizzle said:
:wave: Welcome to TFP!!!

I would agree with Dave that nothing really jumps out a that bad. You seem to have a pretty good grasp on things like the TA dropping due to automation of the acid addition to counter the pH rise due to aeration ... that puts you leaps and bounds ahead of most first time posters ;)

Your CH could certainly start to be a problem as it continues to rise due to the apparent exclusive use of cal-hypo.

Are you prohibited due to regulations from using any stabilizer (CYA) in the water? If not, we generally suggest a level of 20-30ppm even for indoor pools, not for the protection of the FC from the sun, but for the massive buffering effect on the chlorine. You could make the water a LOT more gentle on people by maintaining the same 3ppm FC level, but having some CYA in the water.
Looking at this chart showing the active chlorine level: http://richardfalk.home.comcast.net/~ri ... l/HOCl.htm
For a CYA of 0 and a FC of 3ppm, the active HOCl is 1.45ppm
Raising the CYA up to 20ppm, the active HOCl drops to 0.067ppm .... that is over 21 time LESS harsh than currently, but still perfectly safe.
Of course, depends if you are allow to use it or not in your jurisdiction.
Click to expand...

There are actually absolutely no regulations that I can find for my county (Alabama doesn't have state-wide regulations for pools), and we do have a bucket of cyanuric acid that was perchased in the past but never used. Would you suggest raising to 30ppm and letting drop to 20ppm before raising back to 30ppm, or something else?

Edit: Also, does that recommendation apply to the spa as well?
 
Thanks for that great pic of the Cal-Hypo tabs label.

It appears to have a proprietary dispenser. Do you have a feel for how long the tabs will stay in the dispenser before dissolving? Have you ever removed one that had been in the dispenser for maybe 20 hours or so?

These tabs are not widely distributed or used so we would like to learn as much about them as we can.

I sorta doubt they are contributing heavily to your pH rise. Probably some other factor like high TA or aeration being more at fault
 
duraleigh said:
It appears to have a proprietary dispenser. Do you have a feel for how long the tabs will stay in the dispenser before dissolving? Have you ever removed one that had been in the dispenser for maybe 20 hours or so?
Click to expand...

I'll have to double check the models next time I'm in the pump room, but I believe the main pool uses the AccuTab PowerBase 3070 (max. 2.7 lbs / hr) and the splash pool and spa use the AccuTab 3012 (max. 1 lbs / hr). Between the pools we use about one 50 lbs container a week depending on bather load.
 
What are you using to test?

The test kits we recommend usually start at 20 or 30ppm, the recommendation really is the minimum you can usually reliably test for. Raising it up to around 30ppm would be fine, you need to ensure the FC never drops below 2ppm (see FC/CYA Chart). The CYA generally does not get consumed (at least not very quickly). If you raised it to 30ppm, likely you would not need to test for it for a few months and then maybe add a bit if needed.

And yes, adding the CYA to the spa would be the same recommendation.

This is really not going to change much in terms of maintenance, but will make the pools must less drying to skin and hair and will not destroy swim suits as fast.

Have you see PoolMath to help calculate dosages?
 
How often do you backwash the filters?
How long are the pumps ran each day?

If you backwash often, I'd start off with about 30 ppm CYA and raise it back to that whenever it gets to about 20 ppm.

Have you ever tested the fill water to see what the levels are in it?
 

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Bama Rambler said:
How often do you backwash the filters?
How long are the pumps ran each day?

If you backwash often, I'd start off with about 30 ppm CYA and raise it back to that whenever it gets to about 20 ppm.

Have you ever tested the fill water to see what the levels are in it?
Click to expand...

Backwash as needed for the main and splash. I wait until the PSI increases about 5 PSI or so (base PSI for a clean filter is about 20 PSI for main pool and 15 PSI for splash pool). This equates to about once every other week. The spa is drained (and simultaneously backwashed) completely weekly.

All filtration pumps are run 24/7.

The fill water was 3 FC, 7.4 pH, 90 Alk last time I checked. I'll test it for CH and CYA tonight.
 
That'll give you a reference for maintaining the water. That fill water is pretty good.

I also wouldn't be afraid to let the TA come down to abot 70 or 80 ppm. There's no use trying to fight it and keep it at 100 or more.
 
duraleigh said:
I sorta doubt they are contributing heavily to your pH rise. Probably some other factor like high TA or aeration being more at fault
Click to expand...

I was quickly looking at Baldwin County Alabama code and came across this. Makes me wonder if maybe the tabs could be causing the PH to increase......


“Calcium Hypochlorite (CAOCl2)” a solid white form of inorganic chlorine found in both granular and tablet forms, it has a pH of approximately 11 and is 65-70% available chlorine. See Hypochlorite.
Click to expand...

If this is the case, then I could very easily see the tabs being a reason for the PH increase. As others have stated however, I wouldn't change much if it ain't broken. :D


Edit.....Upon reading a bit more on the PH of various chlorine maybe the PH isn't affected as much as I thought. Liquid has a PH of around 12 and causes little to no change on PH, so maybe these don't change much too. As Dave stated, we know very little about these as they're seldom used. In fact, I think this is the first time I've ever heard of somebody using them.
 
Leebo said:
[As Dave stated, we know very little about these as they're seldom used. In fact, I think this is the first time I've ever heard of somebody using them.
Click to expand...

I'm willing to bet that the people who designed the facility bought the into the AccuTab brand under promises of ease of use and better water chemistry for "just a bit more money"... Luckily the feeders should have no problem running a different tab should that route be the best though the feeders design is not my favorite.
 
SuzakuTheKnight said:
Luckily the feeders should have no problem running a different tab should that route be the best though the feeders design is not my favorite.
Click to expand...

Warning Warning Warning!!!
Do not use different tabs in the feeder. Trichlor and Calcium Hypochlorite can explode when mixed together.

From the Allegheny County Health Department

There are two main types of chlorinating agents:

Inorganic chlorinating agents such as calcium hypochlorite, lithium hypochlorite, and sodium hypochlorite
Organic chlorinating agents such as trichloroisocyanuric acid, potassium dichloroisocyanurate, and sodium dichlorocyanurate

Organic and inorganic chlorinating agents are not compatible with each other. Many incidents have occurred due to mixing of these chemicals. When combined they can form an explosive mixture.
Click to expand...

How badly you may ask..........
http://www.poolforum.com/pf2/showthread ... micals-mix.


With that said, there really are few positives feeders offer. We really don't know much about Calcium tabs, so I'm not sure just what to suggest if looking to switching to. Without knowing how much per tab you're paying.....and how long these tabs last.......I'm not sure we can make many suggestions.
 
Oh, of course! I should have been more clear on that. I would NEVER put mixed tabs in the feeder together. I would only use a different tab after thoroughly cleaning out the feeder and discontinuing use of the old tab in that feeder.

Edit: And I do mean extremely thorough cleaning. I realize that even a small trace of one type coming contact with another is a HUGE no, no!
 
I can confirm that it is the AccuTab PowerBase 3070 on the main pool and AccuTab 3012 chlorinators on the splash and main. The are rated for 2.7 lbs / hr and 1 lbs / hr respectively, though I haven't confirmed this. I'll try to set up a test.

I've backwashed all the pools and added enough cyanuric acid to bring the CYA up to 30 on all pools. I'll recheck once it has had time to dissolve.

So right now I trying to maintain the following on all the pools:

FC: 4 (Any pool will now close if FC falls below 2ppm instead of the 1ppm it was before adding CYA to the mix)
CC: 0 (I'll superchlorinate should it reach 0.2 or higher. I've always followed the FC = 10 x CC rule for superchlorination. Does this still hold with CYA present?)
pH: 7.4
Alk: 100 (I'm gonna try to stagger the changes I make. Once the CYA and FC changes are stable, then I might lower this.)
CH: 250-400 (According to PoolMath, I'm not at risk of scaling unless it really gets up there, but I'll try to keep it under 400. I think the 500 CH in the main pool might be affecting clarity just a bit.)
CYA: 30

Also, I've re-tested the fill water, it is now:

FC: 0 (dpd test)
CC: 0 (dpd test)
pH: 7.3
Alk: 120
CH: 260
CYA: < 30
 

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