HIGH Calcium

I have a 10 year old gunite pool, using bleach for past 12 months as a sanitizer and for shock. Ch is approx 550, drain and refill is not am option as my fill water is approx 350. I have been constantly fighting rising Ph. I lower it to 7.2 and in a few days it is in the 8.0 range. TA is 100.

My questions are:
1. Would it benefit me to raise my TA?
2. How high should I go?
3. Will that help to stabilize my Ph?
4. Will it have any positive or negative effects on my Ch?

Thanks in advance for your help. This forum has been a great asset in helping me enjoy my pool and save money at the same time.

DerrikM

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Originally Posted by derrikm

I have a 10 year old gunite pool, using bleach for past 12 months as a sanitizer and for shock. Ch is approx 550, drain and refill is not am option as my fill water is approx 350. I have been constantly fighting rising Ph. I lower it to 7.2 and in a few days it is in the 8.0 range. TA is 100.

My questions are:
1. Would it benefit me to raise my TA?
2. How high should I go?
3. Will that help to stabilize my Ph?
4. Will it have any positive or negative effects on my Ch?

Thanks in advance for your help. This forum has been a great asset in helping me enjoy my pool and save money at the same time.

DerrikM

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1. no
2. 125 is the highest. 100 is fine. Don't go higher.
3. probably not. Something else is driving your ph up
4. Negative. At best no effect, but go too high and your pool will go milky--I'd bet money by 150ppm you'd have cloudy water and at 200ppm I can practically guarantee it.

Some people occasionally find that bleach drives their pH up--it has pH, I believe, of 11. Also, new concrete pools drive up pH as they cure. Has yours been re-plastered or otherwise treated?

Where is your CYA reading? (stabilizer) If it's very low, then Tri-Chlor pucks or Di-Chlor powder would be ideal instead of bleach. Both are very acid. But if CYA is 50 or higher, it would be a mistake.

Draining your water and refilling would lower your CH to 350--that's a good # for a concrete pool--200-400 is recommended, but 550 is too high. If you use Poconos's plastic sheet method you can do a full water replacement with no risk of the pool floating out of the ground. You said it's not an option but I see no reason not to use it...Again, CH=350 is good for your pool, but 550 is too high and MAY be part of your problem.

There are other approaches and others can chip in with them.

Do you have the option of using softened water, that would help to lower your CH between backwashes and rainstorms? Just a thought.

Pat

You can always hook up a regular water softener and run the pool water thru it. Works good, but does take a lot of time and effort, and does add salt to pool (not an issue if using SWG). My plaster pool was up to almost 800ppm of calcium hardness - took 2 weeks to drop to 200ppm using a Sears home water softener and a 1/2 hp submersible pump

Mrmrk49, Can you explain in more detail how you set up the pump and water softener?
Thanks!
--Sigrid

To run pool water thru regular water softener to decrease hardness:

I used a 1/2 hp submersible pump, connected with garden hose to water softener - use 5/8" dia hose as short as possible to get max flow thru softener. Outlet from softener was run back to pool using another short piece of garden hose just laying on the edge of pool (with a weight on top so it wouldn't move.).

You need to accurately measure the flow rate of the submersible pump thru the water softener and back out to pool - just use a 5 gallon bucket and time how long to fill up, convert to gallons/minute.

Next, you need to know hardness of pool water, and softening "capacity" of the water softener, easiest to calc if both in "grains". If I remember right, PPM = 17.1 X Grains. So if your CH water test shows 600PPM, then that equals 600/17.1 = 35.1 Grains/Gallon.

If your softener has a capacity of 35,100 grains, that means it can remove the hardness from approx 1,000 gallons of pool water. Now, you take the flow rate of your softening system and calculate how many hours it will take to run that 1,000 gallons thru. Typical flow rate may be 5 gal/min, 300 gallons/hour - so it would take a little over 3 1/3 hours to soften 1,000 gallons.

Then you would need to flush the softener - hook the inlet to tap water, outlet to run to drain. This is hte biggest hassle - switching the hoses back and forth for the flush mode. Flushing takes a few hours, then re-connect to soften mode.

I suggest you buy some of the cheap test strips that have hardness test on them, and use to check that water going to pool is nice and soft when you first start, and that after the 1,000 gallons have been ran thru, the water coming out the softener should be hard.

Gets trickier now - as you soften the pool water, your calulations will need to reflect the new average hardness of the pool. For example, if pool was 20,000 gals,and you softened 1,000 gallons to 0 hardness (it won't really hit 0), the new average hardness of the pool is 570 PPM. It's actually more intuitive to calculate it in Grains : 20,000 gal X (600 PPM/17.1 ) = ~700,000 Grains of hardness. You took out 35,000 Grains, so now there is 665,000 grains in 20,000 gallons.

So as you go along, the time cycles will get much longer - at 300PPM, it will take twice as long to remove 35,000 grains of hardness.

My pool was about 20K gallons, CH was >700, my pump ran ~ 4 gallons/minute, and it took me two weeks to soften down to 200PPM (but my tap water is 85PPM, so they didn't help)

Good luck
Mike K

ps : double check the PPM to Grain conversion - I can't remember where I found it!

Would draining 10000 gallons from the pool and refilling it with softened water result in dropping the CH from 600ppm to 300ppm? The fresh water would help in other areas too if there problems (TDS, etc).

Instead of water softener can you add salt directly to your pool to lower hardness?

I read some people add salt to help hardness(just enought so you can barely taste it).

but I can't find any information how salt effects equip or how much to add or where to buy the salt. do I actually buy from a pool store?:eek:

thanks,
scott

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Originally Posted by slater1182

Instead of water softener can you add salt directly to your pool to lower hardness?
Salt won't lower hardness. Water softeners have an exchange resin in them that is loaded with sodium ions by the brine solution that goes through them in the regeneration cycle. Then when the hard water goes through the resin it exchanges the sodium for the calcium and magnesium in the water. The resin is now loaded with calcium and magnesium which is exchanged out and removed during the regeneration and backwash cycles and the resin is loaded with sodium again.
I read some people add salt to help hardness(just enought so you can barely taste it).
Phosphates will lower hardness by precipitating out calcium and magnesium (that is why they used to be used in detergents) and some phosphourous compounds (usually phosphonic acid derivatives) will sequester calcium much like they do other metals (calcium is a metal) Salt will only make the water 'salty'. You have just added sodium to the calcium and magnesium in the water but haven't removed anything.
but I can't find any information how salt effects equip or how much to add or where to buy the salt. do I actually buy from a pool store?:eek:

thanks,
scott

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Hope this clarifies things.

I do this for a living, and no, adding salt directly to the water will not help, as stated above. In fact, you will only be adding to the total impurities in the water (your total TDS and TNDS {total disolved, and total non-disolved solids})

However, using a soft water system as described above will take you some time, and use quite a bit of salt. I am fortunate enough to have 2 systems, and based on my hardness coming in (about 15 gpg) I have about 2200 gal capacity maximum- filling my 7000 gal pool, I used 60 lb of salt... each area will be different depending on how your city supply is, and where it comes from, here in FLA , it is ground water, usually very very hard.

The ratings are based on how much salt is used during the regeneration cycle, based on that, the water will flow to 0 gpg, if that amount of salt was not used, your water will be soft-er, but you will only be getting 80% and less the more water you run through the machine.
(i.e. 35000 grain unit {which is a inacurate number, check with WQA for all of that data, only a few units out there that will do that amount, acuratly} anyway, 35000 grain unit needs about 15 lb of salt to regenerate, to give it a 35000 grain capacity, or what we refer to as start capacity. Most units sold are set to 50% or less, to prevent the media (resin, or resin/carbon, or other combinations) from deteriorating too quickly- and use only about 5 to 8 lb of salt, giving them an actual 17000 grain capacity...


the above method will work, it will just take some time. AND, do make sure you don't let the backwash of the softener drain on your grass, it WILL kill it most of the time! (brine rinse is usually at total salt to water saturation)

anwyay, hope this helps in some way, or at least educates a bit on water treatment... I highly suggest to anyone else reading this, if they have vinyl, or fiberglass, to fill entirely with soft or treated water (0 hardness) the water feels incredible!