newbie chemical question - confused :S

[patty]

Hi, we've had our Optima (485 gals) for about 2 1/2 weeks now and iI've been religiously following Vermonters method.  The chemicals were behaving just as I expected until today....

I've been adding 2-3 tsp dichlor after usage at nite (depending on which combination of 2 adults, teenager & 8 year old has been in tub).  Next morning Free Chlorine is in "ok" range, Alk and Ph have been right on also.  

Questions

1)  I had been testing after 20 minutes but chlorine was always between 3-5 ppm consistently so I stopped doing the test after 20 mins.   "OK" for Chlorine on my test strip is 1-3 ppm.  In the morning its usually on the lower end of "ok".. meaning 1ppm.  Should it be higher than 1 in the morning?  Am I putting enough in at nite?  Is it ok to use at 1ppm?  

2) I shocked with 4 TBS of MPS on Monday morning.  Used the tub Monday nite and added the regular amt of chlorine after.  Today(wednesday) I tested for first time since shocking and chlorine ws low (.5) so I added 3 tsp.  20 minutes later chlorine had jumped up between 5 and 10 ppm.  Whats up with that?  As I understand it, shocking reactivates free chlorine but I don't understand how it can be 5-10 after I only added a tablespoon of dichlor.   I'm going to test again and see if its come down but I am not used to having the chlorine so high.  


The only other chems I've added to the tub is de-foamer.  Before our "no clothing allowed" rule my teenage daughers friend was over and wore t-shirt and shorts (OVER a bathing suit.. no idea why!!!!!!!) and we had a problem with foam for days after.  

Thanks in advance.  Patty

[George]

Clorine disipates over time.  The method you use is to sanatize after use then by the time you use the tub again the levels are real low for use.  What is happening is what you should expect.  If you added the Clorine this morning without using the tub the levels will take longer to disipate.  You are doing everything right, you are OK.  If the Clorine level isn't below 5 ppm before you are ready to use the tub, just run the jets with the lid open for a while with the air valves open and it will drop fairly quickly so you can use it.

[svspa]

patty,

1ppm is no problem to soak in, the plan for dichlor dosing is to get down to near zero when you want to soak.

You don't want to leave your free chlorine level at zero for very long. But as long as you are controlling it you get it down near zero when you soak and immediately after soaking you add dichlor to kill anything you may have introduced into the water.

I wouldn't think it's at all unusual for a tablespoon of dichlor to raise your FC to 5-10ppm if your tub was already really clean, nothing in the tub to burn up the FC. Although 5ppm isn't really that high, not sure which end of the 5-10ppm scale you were really at. Some folks consider 5ppm as the minimum you should get the tub to after soaking (especially if you don't have some secondary sanitizer like ozone or N2 in use). If you have a secondary sanitizer than 3ppm may be fine.

Every tub is different though. Depends on size, usage and how much yucky stuff is introduced into your tub. It may take a while for you to figure out your tub's chlorine demand, if it's really clean (what you want) then just a small amount of dichlor can bump up your FC pretty easily.

Steve

[patty]

Thanks George and Steve. I thought the idea was to have minimal chlorine at soak time, but I wasn't sure if 1ppm was too low.  I was having visions of millions of bacteria, amoebas and other invisible nasties doubling every 20 mins... I guess the key is having 3-5 still after 20 mins right?  

Also my pH is usually on the low end of normal (7.2ish). Once in a while it seems to drop below normal.. somewhere 6.8-7.2.  It's hard to read pH on my strips (pool check 3 in 1) because the green is a different shade from the color chart.  After searching for low pH I added a couple of tablespoons of baking soda and it seems to be back up to normal.   Total alkalinity and free chlorine are easier to read on the strips.  Are some test strips better than others as far as color matching?    Thanks Patty

[gores95]

Thanks George and Steve. I thought the idea was to have minimal chlorine at soak time, but I wasn't sure if 1ppm was too low.  I was having visions of millions of bacteria, amoebas and other invisible nasties doubling every 20 mins... I guess the key is having 3-5 still after 20 mins right?  

Also my pH is usually on the low end of normal (7.2ish). Once in a while it seems to drop below normal.. somewhere 6.8-7.2.  It's hard to read pH on my strips (pool check 3 in 1) because the green is a different shade from the color chart.  After searching for low pH I added a couple of tablespoons of baking soda and it seems to be back up to normal.   Total alkalinity and free chlorine are easier to read on the strips.  Are some test strips better than others as far as color matching?    Thanks Patty

I think you will find most experienced tubbers on this forum recommend the Taylor Test Kit 2005.  I just bought one from Docs store:  http://www.rhtubs.com/store/test-kits.htm

I too am currently using test strips and they are indeed hard to read.