Help!! New Pool Owner And The Chemical Tests Are All Over The Place. What Should I Do?

by Chris Larkin
(London UK)

We've got a pool in a house my father in law bought. It's a salt-water pool and is 20,000 U.S. gallons volume.

A test yesterday showed the following readings:

pH - 6.2

Chlorine - 8

Total Alkalinity - 40

Stabilizer - 10

These all seem to be well outside the "safe" zone but I don't know what to do first. I've read through the details on here, some great information but my problem is knowing what to add now, and how much.

I'd love to go swimming next week! The pool is in France if that makes any difference (it's 30 degrees at the moment).

Any help would me much appreciated. Thanks for a great informative site.

Thanks for stopping by Chris and for the compliment

I've cleared up hundreds of green swamps that people have called pools and have vacuumed for thousands of hours, so I promise your pool and Summer can be saved.

First, here are some pages that you might want to look at:

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

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

What Can I Do About A Chemical Mess During Pool Start Up?

I always start by telling people to get a Taylor FAS-DPD K-2006 pool water test kit. All that information can be found in the links above. The chlorine is a bit high, but it will come down on its own, so don't worry about that. If the chlorine stays a bit high you lessen the risk of pool algae while you're making other adjustments.

First, you should get the alkalinity in line, between 80 - 100ppm. You can go to 120ppm and still be in range. Go to these pages to learn about that:

Pool Alkalinity

Total Alkalinity

For every 10,000 gallons and an increase of 10ppm, you'll need 1.5lbs. of sodium bicarb. Sorry, I don't know the metric equivalent. To raise your pool alkalinity up 60ppm to 100ppm, you'll need about 16lbs. of bicarb. Be sure you read the alkalinity page and adjust it with the pool pump off.

DON'T dump in the bicarb. or any chemical, all at once. Do little adjustments at a time, perhaps 2 - 3lbs. or so. Allow for a full water turnover, maybe 8 - 10 hours, then retest. Using bicarb. might affect the pH as well, so you'll be increasing them at the same time, but more so with the alkalinity and the pump motor off. To increase the pH, you can go here:

Swimming Pool pH Levels

You can use either soda ash or 20 Mule Team Borax to raise the pH without much happening to the alkalinity. Your chlorine will be very active at 6.2ppm pH. Obviously you won't want to swim until the pH level gets 7.2ppm or above.

Next is the stabilizer. You can chlorinate with Dichlor. This has the chlorine stabilizer in it, but be careful as the stabilizer can get out of hand quickly if you use too much of it.

A chlorine chart including Dichlor can be found here:

Swimming Pool Chlorine

For every 10 ppm chlorine added by Trichlor chlorine, it adds 6 ppm cyanuric acid (CYA) or stabilizer. Dichlor is a fast-dissolving powder, but for every 10 ppm chlorine that it adds, it also adds 9 ppm to CYA. You're getting both the chlorination and the stabilizer at the same time.

Once the CYA/stabilizer is between 30 - 50ppm, use either liquid or chlorine granules for maintenance. If you have hard fill water, use liquid chlorine.

Technically, you can swim at an 8.0ppm chlorine level, but only if you really need to. The most important things are these:

*Test with the right test kit. Record the readings in a ledger.

*Make an adjustment

*Allow for a full turnover of the water

*Re-test and make another adjustment if needed.

Too many people are impatient and want it "right now". It won't be right now, but a week, no problem. Make small adjustments, test and re-test, and by next week you'll be swimming. Hope this helps and have a fun and safe swimming season.


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Total Chlorine & Phosphate Problems...What Should I Do?

by Bill
(Pittsburgh, PA)

I live on a heavily wooded lot just north pf Pittsburgh Pa. I have a 20x43 Lazy L in-ground vinyl lined pool (still orig liner).

Pool was put in in 1998 so we are in the 14th season. I pay very close attention to the pool.
I use primarily Bioguard chemicals.

Pool was perfect for first 11 years then I started having chlorine demand problems. Two years ago was my first problem. I had no free chlorine in the pool. I became very confused with all the different advise I was receiving.

One company said I had phosphates in the pool and needed to floc to get rid of them. The bioguard dealer did a water analysis and said I needed to put 50 pounds of shock in to get past the threshold.

I did this and it took two full weeks in the middle of the season for the levels to come down enough to use (and the shock cost $500). But it worked and we got free chlorine back in the pool.

This year I have a lot of total chlorine 4.5 - 5, I think, and just a little free chlorine - 2 ppm last week and down to .5 ppm now.

The pool company again is telling me that the phosphate level is very high and that is the problem.

I am very confused and not sure what is the right thing to do.

Thanks for the question Bill

I'll address the phosphates first.

Phosphates are food for algae. If you go into your pool store and say you have phosphates and need a phosphate remover, they'll be more than happy to sell you a testing kit and several bottles of phosphate remover.

The question is this:

What's the chlorine for? It's to kill the algae and bacteria in the pool. If the chlorine is doing its job, then algae isn't a problem.

If there's no algae, and your water is clear, then why would you need a phosphate remover? To the best of my knowledge, it's safe to swim in a pool with an elevated phosphate level.

Next is the 50 lbs. of shock for a 35,000 gallon pool.

When I shock the YMCA pool (80,000 gallons) I use between 23 - 25lbs. of granular chlorine. This will bring the chlorine level up to 20ppm.

50lbs. of shock in a 35,000 gallon pool is way too much overkill. You can go here to find the charts you need for a pool shock that is adequate for your pool:

Swimming Pool Chlorine

Pool Shock

Pool Chlorine

You were probably told that you have "chlorine lock" or something similar. This is told to pool owners when they don't know what else it is.

Chlorine will go up and down. There really is no "lock". If you were locked in a 2.5ppm chlorine without needing to add any more chlorine, that would save you alot of chemicals.

But it's not true.

You need to test for chlorine and cyanuric acid (CYA), the stabilizer for your pool. The links above go into detail about that. Keep your chlorine level between 1.5 - 3.5ppm and cyanuric acid 30 - 50ppm.

You can shock with Dichlor, which is a stabilized form of chlorine. The CYA can increase quickly when you use Dichlor, so you'll need to be careful.

For every 10ppm of chlorine add with Dichlor, you'll also raise the CYA by 9ppm. I also recommend using a Taylor FAS-DPD K-2006 pool test kit.

Pool Water Testing

Water Testing Kit

Hope this helps and good luck with your pool.


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