Fine Tuning a Salt Water Pool

[Chris1]

What Watermom is trying to say is that FC (free chlorine) + CC (combined chlorine) = TC (total chlorine). Combined chlorine is USED UP chlorine--you want this reading to be 0.

FC (5) + CC (0) = TC (5) --> Here, all the chlorine is Free chlorine sanitizing your pool.

However, if FC is (2) and the CC is (3), your TC would still be 5:

FC (2) + CC (3) = TC (5) --> In this scenario, you would have more combined chlorine in your pool than free chlorine.

Although I've never seen a 'tablet drop' test that you have, I'm pretty sure it won't measure the FC and CC separately; therefore, you are getting a TC reading. A good test kit, as previously mentioned, will provide you with these separate readings and save you a lot of confusion.

Hope this helps!
Chris

[waterbear]

OK, here goes. I am not going into the chemistry behind this now but it has been discussed at length here and in other forums but here is how to set up your SWG. Realize that all these points interact so just doing one without the others is pointless. This does work and there are many who can attest that it does! In fact these are the water balance tips for SWGs that are posted on another pool forum that sprang out of this one. However, the groundwork for all this was laid out and documented on here first!

1) Determine the pump run time you need for proper filtration and turnover in your pool. This can be run as one continuous cycle or broken into smaller cycles. if you break it down make the breaks at even multiples of your cells reversal time (for example, Goldline units reverse polarity every 100 minutes and Pool Pilot digital units have a user selectable reversal time with a default of 4 hours.)

2) Adjust your cell output to maintain a 3-5 ppm FC with your given pump run tme. (I know this does not agree with the Best Guess chart but this does work with a SWG system and has been documented time and again!)

3) MAKE SURE YOU ARE RUNNING YOUR CYA AT THE MANUFACTURERS RECOMMENDED UPPER LIMIT! (normally 80 ppm or 100 ppm, depending on the manufacturer). I cannot stress enough how important this becomes to proper pH control!
If you cannot maintain the FC at the 3-5 ppm range and all the above conditions are met it means your cell is really undersized for your pool. You will need to increase the pump run time. Some manufacturers are more conservative (Autopilot, Goldline) than others (Zodiac) when they rate the gallonage a cell can accommodate!

4) LOWER YOUR TA TO 80 PPM OR LOWER. Once again, I cannot stress enough how important this becomes to proper pH control! If you have a plaster or fiberglass pool make sure your calcium is in the neighborhood of 350 ppm or higher to maintain 'water balance'. (don't worry, if you follow this you will be 'in the ballpark! )

5) Adjust the pH to 7.6. (If it is lower than this do nothing, it will climb on it's own--unless, of course it's REALLY low, say below 7.2, then start adding the borax to bring it up!) Monitor it daily until you know your pool. When it reaches 7.8 add enough acid to lower back to 7.6 but not lower. (This is where an acid demand test becomes very useful. The Taylor K-2006 does include this test!) The lower you place the pH the faster it rises! We are trying to minimize how often you will need to add acid while at the same time trying to prevent pH spikes that can cause all types of problems with a SWG pool! Soon you will know how much acid to add and how frequently you need to add it to maintain your pH. Your pool maintenance just got easier!

6) This step is optional but HIGHLY recommended since it will lower your chlorine demand and further stabilize your pH.
Add borates to 50 ppm. Once you do monitor your FC because, in many cases you will need to lower your cell output to keep your FC in the 3-5 ppm range.
You will also find that your pH will comfortably settle around 7.6 to 7.7 for a longer period of time than before and you will need to add acid less frequently and/or add less acid each time!
I went from about a quart every two weeks to about a cup or so every 6 weeks and have gone as long as 3 months without needing to add any acid to my pool!(fiberglass so it's non reactive,but I have seen benefits in with all pool surface types). I have had customers that have had similar experiences.

To read a detailed account of my first experiment with this read this thread
http://www.poolforum.com/pf2/showthread.php?t=4712
To read the conclusion I came to from the initial experiment (which I have seen repeated time and again in customer's pools and also on other forurms)
http://www.poolforum.com/pf2/showthread.php?t=5419
The reason I did thiis was to see if the claims made for Proteam Supreme (expensive borax), Bioguard Optimzier (expensive borax) and Mineral Springs (their expensive salt mix with borax) and Natural Chemistry's Salt Water Magic (another expensive salt mix with borax) were true or not. Guess what, they are true! (and I live in the same town where the original Proteam test pools were located back in the 80s when they were testing this so I have had the chance to talk to a few people in the industry that remember those experiments).

For a quick update and condensation of the link I posted above, the borates can be added with borax and muriatic acid or by adding boric acid. I have only used the borax and muriatic acid and also Proteam's Supreme Plus which is their pH neutral mix of borax and boric acid.
60 oz. by weight of 20 mule team borax will raise 1000 gallons of water 50 ppm and requires 30 ounces of 20 baum (31.45%) Muriatic acid to maintain the pH.
(12 oz. borax raises 1000 gallons 10 ppm and needs 6 oz acid)

Half the needed amount of borax is dumped into the pool and then half the required acid is then added slowly in the return stream (or diluted in a 5 gal bucket of pool water one or two quarts at a time and then poured into the pool).
Brush the pool to mix the chemicals
Add the second half of the borax and the rest of the acid, brush again.
Circulate for 24 hours non stop then return to your normal pump run time.
Check pH and borate level in 48 hours. If pH is low but in range you are done, If it is high, lower it to 7.6
Actually, I have checked my pH and borates about 2 hours of continuous circulation and if the pH is anywhere between 7.2 and 7.8 I have gone swimming.
For testing borates the LaMotte borate test strip have proven themselves to be superior to all the other strips on the market and provide enough precision to get your borates into the recommended window of 30-50 ppm. I have checked them against the Proteam borate titration test kit time and again they are certainly well in the ballpark! The Proteam test kit is expensive, difficult to find, and not the easiest test to do, btw!
The AquaChek borate strips are much more difficult to read than the LaMotte and seem to have a much shorter shelf life.

I hope you find these tips helpful. They do work, but like I said, onl if you do them all and not just pick and choose. Any one of them will help but when done together the results lead to what the SWG manufacturers promise, a pool that practically takes care of itself!

I hope you find this helpful and if anyone is interested in the actual chemistry then I (and I am sure, chem geek) will be glad to explain it to you. However, just about all of the chemistry info is already here in the forum, much of it in the China Shop!

[BigTallGuy]

Wow! Excellent Post. Thanks Evan. I suspected that the FC reading on a salt water pool could be Lower than traditional Chlorine, and you just confirmed it. I noticed that when I cut my FC numbers down that eye irritation complaints went down too. My pH, TA, and CYA were the same, the only difference was when I cut the "On-Time" back to lower the FC.