Trichlor vs. Cal hypo... anyone use Cal Hypo?

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Pcmaker

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Jun 7, 2012
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Las Vegas, NV
I'm thinking of switching our public pool from Trichlor to Cal Hypo due to high CYA issues. I can't get the CYA level below 60, thus my FC has to be much higher than 5ppm, which is the highest the local health department allows it to be at. I'd rather deal with high pH issues.

Only problem is the Total Alkalinity levels. If the pH is constantly high, I have to keep adding acid, which will lower the pH, but will also lower the TA levels.

Anyone have any experience with this?
 
Cal Hypo adds calcium. If you have high pH and TA, that will lead to scaling.

Can you post a full set of test results?
 
The sale of Cal Hypo here in the southwest desert should be a crime.

Your fill water has a CH of 250 ppm or more. With evaporation your pool CH will increase by at least 2X in one year.
 
Cost isn't an issue as it's not coming out of my pocket. I can't switch to liquid Chlorine because we do not have the room in the pump room for it. This is a commercial pool. We dump water and add fresh water in daily. This is what I've been doing to fight the CYA levels going up so high, but we dump 1/5 of the pool water every day and we still can't get the CYA level below 50.
 
If you absolutely cannot do liquid chlorine and your CYA levels are high but your calcium hardness level is manageable then you can certainly use cal hypo for chlorinating. You will just have to watch your calcium hardness level as every day you will be adding a few parts per million of calcium that will eventually accumulate. This won't be much of an issue with the 1/5th daily water exchanges but eventually I imagine you will stop doing those exchanges when you get your CYA level back to normal which will then make the daily calcium addition more of a concern. Just be aware that it clouds water and like you said, you will have to add acid more often as it can make your pH rise a little.
 
What are you testing the CYA with? It should certainly be dropping if you are replacing 1/5 of the water every day. How much Trichlor are you adding everyday? Pretty easy to do the math on how much CYA you are adding with the Trichlor and then removing with the 1/5 water replacement.
 
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I use a Palintest photometer to test chem levels. It's what the health departmet uses during inspection.

I use an ORP controller to feed trichlor, so it feeds whatever is necessary in relation to CYA levels. The FC is around 7ppm on average in the morning

I'm looking into SWG as well, as the only drawback I've read is that it's slow to add Chlorine to the pool. I'm not sure how big it is and if it can be installed into the current setup we have.
 

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SWG's do add slowly, but more than quick enough to feed the pool the chlorine it needs. The cell just needs to be sized properly. We recommend getting a SWG that is rated at least 2x larger than the pool volume, so in your case rated for 80k gallons. You will find that you may need 2 of the SWG cells to get the capacity you need.
As for actually getting it installed in your system, it is very likely that you can find room for it. The cells themselves are not too large and there is the additional electronic box that can be installed on a nearby wall.
Post a picture of the equipment pad if you like.
 
Like others have said, liquid chlorine is the way to go. 38k gallons is not that big for a commercial pool. 2 gallons of 12.5% bleach will raise FC in your pool by 6.6 ppm and you won't be raising CYA. I would add a SWG. Yes it is slow to add chlorine but it does it constantly when the pump is running and therefore allows lower FC levels to properly sanitize the pool.
 
I use cal-hypo early and late in the season, when big box stores around me stop carrying 10% liquid chlorine, since my CH is pretty low (110 to start the season, 130 now), and the cal-hypo I order online is cheaper than buying 10% L.C. from the pool stores. I'm not sure exactly what you are asking, but it works just fine. I pre-mix it in a bucket. It doesn't affect my PH or TA.
 
I am well aware of that, but that is not the way you originally wrote it. ;)

In any case, sounds like it might be working better for you than most. Higher CYA values tend to reek havoc on the ORP reading this messing up your FC levels.
 
And what happens if you leave the setting at 650 but your CYA increases to 70ppm?
Does the FC increase?

The ORP reading is affected by many parameters in the water. Again, sounds like you are having better luck than many of our members if your FC is stable. They seem to become unreliable as the CYA is higher.
 
jblizzle said:
And what happens if you leave the setting at 650 but your CYA increases to 70ppm?
Does the FC increase?

The ORP reading is affected by many parameters in the water. Again, sounds like you are having better luck than many of our members if your FC is stable. They seem to become unreliable as the CYA is higher.
Click to expand...

That is the issue. I have to dump a ton of water every day just to keep the CYA at 50-60. The higher the CYA, the higher the FC is because the controller compensates for it. 650 mV is the minimum ORP recommended as it will set the FC to the minimum "target FC" based on the CYA level. 50 CYA target FC is around 7ppm.
 
@Pcmaker FYI, Pentair makes commercial SWG cells that can be ganged together with one being the Master and others Slaves to handle the needs of large pools. A SWG system with a CYA of 60 needs a FC of 4. See FC/CYA Levels

Is this pool outdoors or indoors?
 

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