View Full Version : SWG for use with liquid bleach?
bearsprague
05-23-2014, 03:08 PM
If I am using liquid bleach which adds salt, the TDS increases in the pool. Can I use a cheap SWG to use the salt in the pool to help with the TDS and the chlorine?
Pappy
05-24-2014, 04:03 PM
I'm not an expert by any means, but I've read several threads here that say TDS is a "Pool Store" way to sell you more stuff that you don't want in your pool. I don't think you'd be able to add enough bleach to get salt levels high enough for a SWCG to make any difference.
Pappy
kelemvor
05-24-2014, 05:32 PM
A SWG won't help with TDS. The amount of salt added to a pool by adding liquid chlorine is so small that it's probably not even measurable with commonly available test kits. Most swg's require you to add around 3000ppm of salt to your pool water for them to operate, so it would have the opposite effect you're looking for.
http://www.poolsolutions.com/gd/swimming-pool-salt-water-chlorine-generators-faq.html
What is a salt water system?
A salt water system or “salt water chlorine generator” (SWCG, SWG) is used to replace traditional chlorine with chlorine produced from salt in the pool water.
How does it work?
Salt, or sodium chloride, dissolves in water separating into sodium (ions) and chloride (ions). By passing a low voltage electrical current between special metal and through the water, the SWCG then converts the chloride into chlorine in a process called electrolysis.
The newly created chlorine creates a chlorine residual, and is available to sanitize the pool. When it is used up, it changes back to chloride, and allowing the process to start over again.
Why the concern over TDS? Is the pool store trying to sell you something to remove them?
chem geek
05-24-2014, 09:15 PM
For every 10 ppm Free Chlorine (FC) added by chlorinating liquid or bleach, it also increases sodium chloride salt by 17 ppm after accounting for chlorine consumption/usage. So if your daily chlorine usage is 2 ppm FC, then the salt level will increase by around 100 ppm per month if there were no water dilution. Note that ANY source of chlorine will increase the salt level because chlorine becomes chloride salt when it gets used/consumed. Stabilized chlorine (e.g. Trichlor and Dichlor) increase the salt level at half the rate (so around 50 ppm per month), but they increase the CYA level as well (at around 36 ppm CYA per month for Trichlor and 55 ppm CYA per month for Dichlor). Calcium hypochlorite (Cal-Hypo) increases the salt level at a rate in between these two, but it also increases the Calcium Hardness (CH) level (at over 40 ppm CH per month).
CarlD
05-25-2014, 07:27 AM
The bottom line is that the amount of salt bleach or liquid chlorine adds is insignificant compared to the amounts needed for an SWCG, by at least an order of magnitude. Bleach is actually made from brine. I have had pool store guys give me that crud about bleach adding TDS while they were selling LC!
The TDS scare tactic was a fav till they came up with the more lucrative phosphate scare scam....