Shock The Pool & Chlorine Tabs

by Shelley

I would like to know if it is safe to shock my pool while there are still chlorine tabs floating, or should I take the chlorine tabs out first? I don't want to mix the two if I shouldn't.

Your site is great and full of information!! Thank you

Thanks for the question and compliment Shelly

From a chemical point, there's no reason to take the tab floater out. Chlorine tabs are chlorine mixed with a stabilizer. From a shock point of view, you'll want to remove it because you'll want the shock to go to the pool as much as possible.

In fact, remove everything you can in the way of stairs, ladders, etc.. I was wondering why you were shocking the pool? Is it because you have an issue that calls for it, or is it for weekly maintenance? If your pool is perfectly balanced and it's just for weekly maintenance, I'd encourage you to test the combined chlorine (chloramines) first. When they're 0.6ppm or above is when you want to shock.

The weekly chlorine levels will kill the algae and bacteria. You can have this tested at your local pool store or use a Taylor FAS-DPD K-2006 pool test kit.

Pool Water Testing

Water Testing Kit

Hope this helps and have a great Summer.


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Jan 19, 2015
New Pool Set Up & Water On The Green Side
by: Shelley

Well, we just set the pool up and the water is a little on the greenish looking side. Chlorine levels were a little low with two 1" tabs, so I added another to be sure it was getting the proper level.

The pH seemed to be around 7.2 which looked ok I guess. I was just hoping that the shock would clear up the green tint to the water. Is there something else I should do instead?

Thank you for your reply so quickly.

Hello again Shelley

First, I'd like to have your complete chemicals readings. It makes troubleshooting much easier and the process of clearing up your pool will go much faster. You can get this done at your local pool store. Without these numbers I'm just guessing at what the problem is.

You really need to get a good test kit, as stated below. The DPD K-2006 is one of the best. For a newly filled pool without any (or low) chlorine and no stabilizer (cyanuric acid/CYA) you will want to shock the pool with Dichlor. Keep the filter on. This is a stabilized chlorine.

Other kinds of chlorine, regular liquid and granular, are unstabilized and will dissipate within a few hours because of the sun and heat.

Shock in the evening then retest the chlorine and CYA in the morning. You may need to shock again to get the CYA up between 30 - 50ppm.

You'll want to keep the chlorine level up above 12ppm as well as you can. And you may need to manually dose your pool throughout the day to keep it there. Be careful when using Dichlor as it can get out of hand quickly. For every 10ppm of chlorine added with Dichlor, you'll raise the CYA by 9ppm. For every 10ppm of chlorine added with Trichlor tabs you'll raise the CYA by 6ppm.

Once this is done you can use the chlorine tabs to keep the CYA at that level and switch to regular chlorine for weekly maintenance. Don't touch the pH if it's 7.2. It should come up on its own through splashing around and water movement.

It's still in the safe zone and you don't want to add anything else to the pool if you don't need to. Here are the links to my chlorine, shock, and tab pages:

Swimming Pool Chlorine

Pool Shock

Pool Chlorine

Chlorine Tablets

Pool Chlorine Tablets

And here are some links about pool start up on the Q&A page:

Swimming Pool Questions and Answers

My First Pool..How Do I Add Chemicals & Make Adjustments?

Above Ground Pool..Need To Know About Chemicals & What To Do..

Go to the Q&A page in the "Start Up/Opening A Pool" category. There's lots of really good info. there.

Hope this helps and let me know how it turns out for you.


Jan 19, 2015
Can't Do The Chemical Readings
by: Shelley

I dont think we have a pool place here in this dinky little town, but my boyfriend works at the water plant here and I was able to get these readings through him.

I hope this helps, and thank you again so much.

alkalinity: 28
iron: 0
PH: 7.6
Chlorine: .06 despite three 1" tabs floating around

He didnt have a way to test for the CYA. Thank you again for your help. Also, how often do we need to run the pump? 24/7?

Thanks for the readings.

The reason they're important is so we'll know what we're dealing with. We need to get them balanced, but there's a way to do it. If you've been using chlorine tabs all this time, the CYA might be a little high.

There's been times when pool owners can't keep the chlorine level because the CYA up over 100, or it's zero. Why does this matter? The chlorine needs to be 7.5% of the CYA and that is 30 - 50ppm. For a newly filled pool with 0 chlorine and CYA, you'll shock with Dichlor to get them both in the pool.

Then, when the CYA is 30 - 50ppm, you stop using Dichlor and switch to regular chlorine for weekly maintenance. If the correct readings are not known, I promise you'll have a difficult time balancing out the pool and you'll get very frustrated. Next to pool safety, taking water tests is the most important thing. If you don't know the CYA, I would suggest ordering a Taylor FAS-DPD K-2006 test kit.

Pool Water Testing

Water Testing Kit

For now, shock with regular liquid chlorine in the evening, then retest in the morning. This will show you how much chlorine you're using up. Now for the alkalinity, which is very easy to fix. You can use sodium bicarb. which is nothing more than baking soda. Get this in the grocery store.

Pool Alkalinity

Total Alkalinity

The links above have charts for your size pool and it's very easy to do. You know the alkalinity is 28ppm and you want to get it between 80 - 100ppm. Add the bicarb. in one spot in the deep end with the pump OFF. Allow this to sit for about 3 - 4 hours, then turn the pump back on and allow for one full turnover. This is normally about 8 hours.

Maybe you can add it in the evening, around 5pm or so, then turn the pump back on at 9pm and let it go all night. Retest in the morning. You may want to do this in a couple of steps, not all at once because you don't want to over shoot. If you do you'll have to add acid to bring the level back down again. Another chemical and added expense.

Don't touch the pH. It's fine at 7.6ppm. With the exception of the few hours the pump will be off for the alkalinity, you'll want to run the pump 24/7. Here's a link to the Contact Me page.

If you would like personal assistance by phone, which would make the process go much faster, I'm available.

Contact Me

I had a route of 50 pools in Arizona, have taken care of and cleared up hundreds of green pools, taken thousands of tests, and have been the pool operator for our YMCA pool (80,000 gallons salt pool) since 2008. Been doing this since 1999.

Hope this helps. Let me know if you'd like personal assistance.


Jul 25, 2016
Shock Treating My Pool
by: Anonymous

Can I shock treat my above ground pool by simply adding extra multifunction tablets to the floating dispenser?

It's best to use liquid chlorine. Tabs are meant to dispense 1ppm FC so it doesn't bottom out. They're not made to superchlorinate a pool.


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