Switching from Salt to Chlorine

[BlueBell]

Hi all,
We have a Salt Water pool and our stone decking is disintegrating. We used a stone called Mexican Creme and the stone guys in town and our pool builder advised us not to use it because they weren't sure it would work with salt. We loved the look and decided to take our chances on it. Sure enough it started flaking at the steps and other entry/exit points pretty quickly. We have spent thousands on sealing to no avail and it is still flaking away.

So...we are thinking of switching to chlorine in order to save the stone decking but we are a little unsure how to pull this off.

First of all, do you think it will stop the disintegration of our stone?
Can we just drain the pool, turn off the SWG, refill the pool, and begin with chlorine?
Is it okay to leave the Salt Cell in the line in an "off" position?
What should we expect for a weekly liquid chlorine usage?
What chemicals are we going to need to put in right away?
Is it a bad idea to drain the salt water into our yard and will it damage the trees and grass?

Thank you so much for any advice you can offer us. We have searched the internet but haven't been able to find much information on going from SWG to Chlorine. Thanks again!

 

[JamesW]

Is the stone a quartz-based stone, such as sandstone, quartzitic sandstone or quartzite, or is it a calcium carbonate based stone, such as marble, travertine or limestone?

 

[BlueBell]

It's chalky and similar to a limestone except that it flakes. Thanks!

 

[duraleigh]

The switch is pretty easy. Pretty much like you said, turn of the SWG and start diluting by drain and refill. Do it in multiple stages (like about 3-4 times. It really doesn't take that much more water and is safer than draining the entire pool at once.

Chlorine usage will vary but it far more an suue of convenience that you give up than it is an issue of chlorine cost.

I ASSUME it will stop the deterioration but that means I have to ASSUME that's what is causing. I have no reason to think that's not the issue but that's not a call I would make until you try it.

For that reason, I might leave the SWG in place, just switched off. Then if the deterioration continues, you at least can return to the SWG.

You won't need any other chemistry.

 

[BlueBell]

Thank you! Is there a risk to draining the pool dry, then refilling?

 

[duraleigh]

Thank you! Is there a risk to draining the pool dry, then refilling?

Do it in multiple stages (like about 3-4 times. It really doesn't take that much more water and is safer than draining the entire pool at once.

Yes, it's pretty small but there nevertheless.....do you have a need to do that?

 

[BlueBell]

We just want to make sure we get every bit of salt out of it. That's the only reason we would want to drain it all the way out then refill.

 

[duraleigh]

We just want to make sure we get every bit of salt out of it.

You won't be able to. Even liquid chlorine leaves a salt residual in your pool. Nevertheless, you should be able to get salt content low enough that it will have no effect on your stone.

 

[Ohm_Boy]

The big danger with completely draining an in-ground pool is that it becomes a large boat to the local water table, and may very literally pop out of the ground. It may be completely safe if the water table is below the bottom of the pool, but unless you know this for certain, you should always leave a couple of feet minimum of water in the pool.

 

[BlueBell]

Thanks everyone. We are definitely going to leave water in it to avoid any problems. Thanks for giving us the heads up on that!

 

[BlueBell]

We've almost finished refilling our pool with fresh water and have gotten most of the salt out and now have another question. We want our water to be as salt free as possible due to the stone erosion. Liquid chlorine seems to add a lot of salt. What is our best chlorine option in order to keep the salt levels low?

Thanks everyone!

 

[chem geek]

With chlorinating liquid or bleach, for every 10 ppm Free Chlorine (FC) you will also add around 17 ppm salt. If you add 2 ppm FC per day for 6 months, then that would be an increase of a little over 600 ppm salt assuming no water dilution. If you were using Trichlor pucks/tabs, then you would add half as much salt (so, 300 ppm), BUT you would be adding over 200 ppm CYA which is far worse. With Cal-Hypo you would be adding over 250 ppm Calcium Hardness (CH) plus some salt (probably around 200 ppm). So really, chlorinating liquid or bleach is still your best bet because they don't add the extra things that are more problematic.

With a reasonable amount of water dilution from backwashing and with rain overflow, you should be able to keep your salt levels under 1500 ppm.

 

[BlueBell]

Thank you so much! That's incredibly helpful. If I go with liquid chlorine I was wondering about the Hasa Liquidator. I think it claims to remove salt from liquid chlorine before it enters the pool. Does anyone know whether it really does remove a lot of the salt?

 

[Bama Rambler]

It doesn't. I had one for almost two years and there was never enough stuff in the bottom to clean it out during the year.

Clorox bleach has lower salt than most others on the market. And in the near future it should have even less salt. So using Clorox bleach should keep the salt as low as you can. However I think you may be overly cautious. There's a lot of difference between even 1,000 ppm salt and 3,000 to 4,000 ppm of salt as far as stone corrosion goes.

 

[BlueBell]

Very interesting. Thank you so much. Do you like the Liquidator? Does it make your life easier?

 

[Bama Rambler]

In all fairness I now have an injection pump. I liked the LQ (liqudator) but since I have tons of leaves clogging the skimmer every day I was constantly having to adjust it. If leaves aren't a problem for you it will work great. It makes it very easy as to hauling chlorine. I only had to fill it every few weeks. My sister now has it and loves it. She doesn't have nearly the leaves I do so it works great for her and she barely ever has to adjust it.

 

[jasonknox]

As far as chlorine usage I have a 35 thousand gallon pool that uses 1 gallon(10-1/2%) per day in the summer months. This winter I have used 1 gallon per week. From March 2011 to March 2012 I used 209 gallons for a total yearly cost of around $360/year for chlorine.

 

[chem geek]

As for my 16,000 gallon pool, I use around 1 ppm FC per day over 7 months during the extended swim season and then around 1 ppm FC every 2 weeks over the winter season with the water cold (around 50ºF). The 12.5% chlorinating liquid costs $3.50 per gallon so the entire season for around 29 gallons costs just over $100. I also add some acid now and then, but that's a lot less in amount and cost.

The reason mine is less is the pool size (16,000 vs. 35,000) and the mostly opaque safety cover that keeps chlorine usage down to only 1 ppm FC per day instead of the more usual 2-3 ppm FC for pools without a cover. On the other hand, my chlorine costs at $3.50 are much higher than $2.05 (after accounting for concentration difference, so 12.5% equivalent).

 

[RobbieH]

BTW, the Liquidator worked fine for my pool, I switched to salt for other reasons. My equipment is all indoors and I wanted everything sealed to protect the car and equipment in my garage.

 

[BlueBell]

Thanks for your input. We really appreciate it. We live in Austin, Texas and our 19K gal pool has medium to high sun exposure. Does anyone know (or can guess) how much 12.5 beach we should expect to use each week in the summer?