Using trichlor and cal hypo

[cmaz]

Hi,

i am newly in charge of a small club pool. i have been provided with a bucket of trichlor pucks and a bucket of granular cal-hypo.

The procedure that has been vaguely given to me is to place a number of pucks in each skimmer basket and then to add cal hypo each day for an immediate CL increase, if necessary (it has been, every day...up to 1000g).

i read the warnings on the trichlor that it should not be used with other CL products, did a little research on the web and saw a video of the two combining to explode!

So, i'm coming for expert opinion...Is this ok?

Right now the pucks are being placed in the skimmers, i've read this is going to be murder on the pipes (because of low pH). If the pool is empty, i have been broadcasting the cal-hypo into the pools deep water, but if it is being used, i have been pouring it into the skimmers instead. Do i need to be concerned about the two chemicals combining? Am i going to blow up our filter? i've read a suggestion to dissolve the cal-hypo in water before adding it, and this seems like a good idea that i will implement for the future. Could i add this to the pool while there are patrons in it, or should it still add it in the skimmers?

Are there any other concerns with using the two chemicals simultaneously? From what i've read, the pucks will decrease the pH, but the cal hypo will increase it...so maybe in at least that respect they might cancel each other out and we won't have need of adding muriatic acid or soda ash?

Thanks for any and all help/advice/suggestions anyone can give me!

 

[reebok]

if you are interested in maintaining the pool properly, you need a good test kit. taking care of the pool that way is a blind way that will lead to problems. pucks in the skimmer won't hurt pvc pipe afaik, but can hurt your equipment if the pump isn't running 24/7. it would also be a great help to post a full set of test results even if you have to get them from the pool store for now. chances are this pool will need partial draining due to high calcium and cya levels.
that said, if you are not interested in maintaining it properly (and I'm not saying that negatively, I mainly mean that it sounds like you got stuck in a position and you have no control over how to take care of the pool except to do what they told you and buy for you) I can tell you that unless the water in that pool is drained yearly, you will soon be looking at algae and calcium scaling. more info about the pool would help too. I recommend you read the following links, especially the pool chemistry part in pool school.
pool-school/read_before_you_post
pool-school/

 

[chem geek]

Welcome to TFP!

Continued use of Trichlor or Cal-Hypo will build up Cyanuric Acid (CYA) and Calcium Hardness (CH), respectively. The following are chemicals rules of fact independent of concentration of product or of pool size.

For every 10 ppm Free Chlorine (FC) added by Trichlor, it will increase Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it will increase CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it will increase Calcium Hardness (CH) by 7 ppm.

Even at a low 1 ppm FC per day chlorine usage, use of only Trichlor for chlorine would increase the CYA by over 100 ppm in 6 months if there were no water dilution. If you used only Cal-Hypo, then the CH would increase by over 100 ppm in 5 months, again if there were no water dilution.

Consider using chlorinating liquid or bleach as a source of chlorine. The main downside is that it would need to be added every day or two unless there was a pool cover.

Richard

 

[frustratedpoolmom]

The longterm effects of puck usage on PH will not be cancelled out by using Cal-hypo.

If you use pucks, you'll need to monitor PH/TA levels and keep them in line with Soda Ash or a combination of Borax and Baking Soda.

Learn how to use the Pool Calculator to accurately determine dosing of various chems.

If you monitor your CH levels, you can alternate between Liquid Chlorine and Cal-Hypo for immediate chlorine increases, keeping the CH in range. As long as the PH doesn't go above 7.8 you shouldn't have scaling issues. But eventually if the level gets too high you should replace water. (Def pre-dissolve the cal-hypo). Is the pool drained for winterizing? What is the fill water like?

People should not be swimming when you are adjusting chems.

Perhaps an inline chlorinator can be installed for the pucks, but they should not be left in skimmers unless the filter runs 24/7.

If they CYA and/or CH gets too high you should have routine water replacement.

Be sure to monitor these levels and keep the FC according to the CYA Chart, or the pool will not be properly santized for bacteria/viruses - plus you risk algae.

You will need your own test kit, Either the TF100 or the Taylor K2006.

If you are going to use pucks, order extra CYA reagent because you'll be testing that on a more frequent basis than normal residential pools.

 

[cmaz]

Thanks for all of your advice and suggestions.

We do have a test kit, but i have only dpd tablets and a pH reagent. The pH has been remarkably stable at 7.6. Chlorine levels have not been so stable.

i don't know how the pool was winterized or if it was drained, but i believe the fill water was facility water from an outside garden hose.

i know that people should not be in the water when i'm adding chemicals, but i don't believe there is any way around this. There are almost always already patrons in the pool when i arrive each day and test the water. The chlorine almost always tests low each morning (< 0.6), so something has to be done. My best solution was, as i said, to pour it in the skimmers. From my reading i was concerned about pouring the cal hypo in the skimmers when there were already trichlor pucks in there, but from your responses, i guess this is not really too much of a worry.

The filter is indeed running 24/7.

Thanks again for everyone's responses and the links!

 

[anonapersona]

There are almost always already patrons in the pool when i arrive each day and test the water. The chlorine almost always tests low each morning (< 0.6), so something has to be done.

Most pools I've seen, including neighborhood pools and country clubs as well as health club pools, periodically shut down for maintainence. The bigger pools clear the pool once an hour for 10 or 15 minutes so the lifeguards can test water and tend personal matters and smaller pools simply post that they anticipate maintenance from 6:30 AM to 7:15 AM and are closed to swimming for that time.

Really, that small downtime is WAY better than suddenly having all the swimmers come down with infections from too low a chlorine content to keep the pool sanitized. I can't stress that enough. I pulled my kids from swim team in part because each spring when the team started practicing, a lot of the kids came down sick with sinus infections and ear infections. After a few years I caught on to the timing of that. Now that I know more about pool maintainence, I know why.

 

[Casey]

O_O .6 is too low!

I know when my dad ran a swim club, he'd do all of the chemical additions at night and/or before the club opened. I also know that when the guards got their break, they'd also test the water and mark it in his book so he knew what was going on around the clock.

As far as low chlorine goes, you must find some way to keep it up! When I got my pool in the beginning, dad said he kept the swim club pool at 10-13ppm just because there were so many swimmers! His swim club pool was always crystal clear! It was a HUGE L shape pool too! Sadly, it's a lumber yard now.

 

[frustratedpoolmom]

.06 is too low, you need to add enough liquid chlorine each day to make sure it stays above the "min" target for FC for the current CYA level. Prevent it from dropping that low by adding adequate amounts of chlorine each day. Obviously the tablets aren't cutting it.

You need a test kit that includes an FAS-DPD chlorine test and a CYA test. You need to do an overnight FC loss test with the FAS-DPD test and you need to confirm your CYA level.

I would post a sign that gives you 30 minutes of daily maintenance time and schedule that for your normal arrival time.

If you look at the chart - with a "public" pool you do want the FC to be 2-3 ppm higher than your backyard pool - so if you have a certain level of CYA- use the "target" as the "min" level...