Poor quality Dichlor granules

[seligman]

What's a good manufacturer of Dichlor granules, and where can I buy it?

The last time I purchased Dichlor at Home Depot (or was it Lowe's, I forget which) there was a new shipment that had just arrived. I selected a jug from this batch but I've discovered that it's extremely weak. Don't know if it's the chlorine itself or the lack of cyanuric acid. I've watched my spa's free chlorine go from 5 ppm to 0 ppm in one day's time, and that's in recently shocked water, with nobody using the spa. The DE filter was recently cleaned as well, so I can't explain the chlorine demand any other way.

FYI, the brand name is "Pool Time" aka Aqua Chem, which is an alias for Recreational Water Products (Chemtura).

 

[bk406]

It's not the chlorine. Something is in your spa thats using it up.

 

[seligman]

What it could be then? The DE Filter was recently cleaned. And the water shocked afterwards.

I've noticed whenever I remove the cap on the dichlor, there is less of a chlorine smell. I realize it's dangerous to be sniffing it, so I don't do it intentionally. But regular chlorine bleach has more of a potent odor than this container of dichlor has ever had.

 

[Sportsman]

What are you testing with and can you post full results. Is the spa in the sun?

 

[zea3]

Dichlor granules have CYA. The only unstabilized granules are calcium hypochlorite and lithium hypochlorite. Please post a full set of test results so we can advise you better.

 

[seligman]

pH - I try to keep it around 7.5, but it rises toward 8.0 frequently because of the aeration of the jets
TA - 90-100
Free Chlorine = Total Chlorine, I try to keep FC at 5 ppm but lately it's been impossible to hold it there
Calcium Hardness = ~300

The spa is in partial sun. I'd say it gets 6 to 8 hours of sun per day. Full sun for just 2-3 hours (around lunchtime).

 

[seligman]

I'm testing with fresh Taylor reagents by the way.

Not that it matters, but we've had this spa for about 6 years, so I'm pretty familiar with normal and abnormal test results. I've tested the water hundreds, probably thousands, of times. While I'm no expert in chemistry, I still feel very strongly this batch of dichlor is bad.

 

[chem geek]

It could just be a weaker brand -- see if the ingredients say it contains 99% Sodium dichloro-s-triazinetrione (or sodium dichloroisocyanurate). If not, then it's got some filler. If it's the more common dihydrate and is otherwise nearly pure, it should say that it has around 55% Available Chlorine.

 

[tim_pool_newbie]

You seem to be missing a few important measurements in your testing.

First, you say "Free Chlorine = Total Chlorine" but that's not true. Free Chlorine (FC) + Combined Chlorine = Total Chlorine. You need to be measuring your Combined Chlorine as this will give you an indication if you have any organics in the water that are causing the chlorine to be used up so quickly.

Also, do you know what your CYA level is? If you've been using dichlor for quite some time, chances are your CYA level is off the charts and your FC is going to be ineffective against combating algae and other organics in the pool. You may be looking at a partial drain/refill to get that under control.

Try to measure and post these levels and the experts will surely be able to help you.

 

[seligman]

What I meant to say is I can't detect a discernable difference between Free and Combined Chlorine. I add the drops to measure the Combined Chlorine and the color doesn't change. Wouldn't that be expected for freshly shocked water?

The ingredients say 99% Dichlor, just like the previous bottle said. When I bought this jug of Dichlor (few months ago) I noticed the difference immediately. What I'm finding now is more and more test results that come back totally clear in color (0 ppm) when Dichlor was last added 24-48 hours before. This very rarely happened with other bottles of Dichlor. I'm also going thru it faster than ever. Within a couple weeks of using the new bottle, my family started asking me, "why are you using more chlorine all of a sudden?" I hadn't told them anything but they picked up on it just by watching me.

Not sure about the CYA level. I drained half the spa when I cleaned the filter. Whenever I've tried the Taylor CYA test, there's no "cloudy" water as they claim there should be, just clear.

 

[chem geek]

If you are using a DPD test kit where you compare the intensity of pink/red against a standard, then you would expect no change in color when adding the R-0003 drops since that means that Total Chlorine (TC) is the same as Free Chlorine (FC) which implies that the Combined Chlorine (CC) is zero, which is what you want. Shocking just raises FC and TC together, but does not create CC. In general, you do not want to have TC larger than FC -- i.e. you don't want R-0003 to make any change in color.

 

[seligman]

While we're on the subject, does the age or storage conditions of Dichlor (or any chlorine product) affect its potency or shelf life?

 

[chem geek]

No, not unless it gets wet.