Filling pool with water passed through a water softener

Total hardness and calcium hardness in pool water.
Scale, calcium buildup, hard water and scaling problems.
Kenric

Filling pool with water passed through a water softener

Postby Kenric » Mon 09 Jul, 2007 02:28

Recently, my pool has started to become green with algae alot faster. I had a water softener which wasn't used, but 2 months ago I bought some salt and filled the water softener with salt. I am just wondering if this has anything to do with my algae problem.

In the past a simple 2 bags of shock would keep my pool in check. I'm putting about 5 bags a week now and still getting a tinge of green. My CYA is high and I'm working on it, but I just don't think it suddenly became high in the past month.


chem geek
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Postby chem geek » Mon 09 Jul, 2007 12:01

If you don't keep your FC level at 11.5% of your CYA level (or at an absolute minimum of 7.5% of the CYA level at all times) then your pool may develop green algae. I suspect this was a coincidence and that your CYA level built up to the point where the FC level you were maintaining was not sufficient. If you use Trichlor or Dichlor which are stabilized chlorine, then your CYA may increase quite dramatically, especially if you do not regularly backwash your filter (if it's sand). With every 1 ppm FC introduced by Trichlor, you also get 0.6 ppm CYA.
Backglass
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Postby Backglass » Mon 09 Jul, 2007 14:59

Your water softener isn't a cause for algae. It simply removes the mineral "hardness" from the water. I have a water softener and for some odd reason the hose bib on the back of my house is from the "softened" line (usually hose bibs are untreated "hard" water). As a result my pool is filled with softened water. The only difference I have seen is that I have had to add hardness increaser from time to time as my pool is cement and my water gets too soft.
Kenric

Postby Kenric » Tue 10 Jul, 2007 09:56

Thanks for the reply guys. I started a new thread with more detail on my problems.

viewtopic.php?p=10575
Dan Y

Filling pool with water passed through a water softener

Postby Dan Y » Sat 14 Jul, 2007 13:04

I have had an ongoing chlorine demand problem this season and one thing that has changed from prior seasons is that we installed a softener over the winter. I was informed by a pool service technician to never fill the pool with water that has been softened using the typical method of ionic exchange with salt. He said it would add unwanted phosphates to the pool. I was hoping to help my high hardness level by using the soft water but I guess this leaves me confused as to whether I should use it or not.
chem geek
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Postby chem geek » Sat 14 Jul, 2007 13:41

Dan Y,

Something about this doesn't sound right. Most water softeners that use ion exchange resins simply exchange the calcium and magnesium ions in the water for sodium or potassium -- all are positive charges. I don't know why he thinks they would introduce phosphates into the water -- that doesn't sound right to me. Besides, even high phosphate pools can keep away algae with the proper level of chlorine -- low phosphates can limit algae growth but high phosphates can't make them reproduce any faster than their best-case limit which is 4-8 hours per generation. If you are restricted in your diet of a needed nutrient, you will die, but if you are offered tons more than you need, you aren't going to grow any faster.

Now there are metal sequestrant products that contain phosphates, but they are not orthophosphates and are not in a form that can be food for algae. Perhaps some types of water softeners use this method, but they really don't remove metals from water -- they just prevent them from precipitating and certainly aren't ion exchange types of filters.

Richard
Dan Y

Postby Dan Y » Wed 18 Jul, 2007 19:47

Thanks, Richard. I'm certainly not a chemist but I agree that it doesn't seem right. I will probably dig a little deeper into his reasoning, based on what you are telling me. It seems like the softened water would be better if the hardness level is edging up. I'm trying to keep the PH slightly lower while the hardness level is up. But the underlying issue is that I gotta sock this demand problem!

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