Maxemily

$$$$$$$$$$ Exactly! There is little margin in a gallon of bleach.

My experience with muratic acid and my 325 gal. tub tells me .4 oz will not do enough for you in the long run. Your PH might initially drop to 7.6, but it will climb again in short order. A better approach might be to drop TA in increments and see where PH stabilizes. If you look at the bottom of the Pool Calculator page you will find an 'Effects of adding chemicals' paragraph. This app. contradicts the calculator section somewhat in that it shows a .57 drop in PH with 1 oz of muratic acid added to your tub. The TA drop looks accurate for you and that is where I would focus, if I were you. Add the oz., check TA to confirm drop accuracy, then check PH and PH again tomorrow. Keep this pattern up until your PH stays where you want it. For what it's worth, my tub likes: TA 60, CH 200, CYA 25, Borates 50, Temp 100. This gives me a saturation index of -0.14 but keeps my PH rock solid at 7.6

Refilled the 325 gallon tub at the end of August and had 30ppm CYA in short order as we use the tub everyday. Water temp in September averaged 95F, in October 97F. I add 3oz Clorox per day. The CYA test is now clear. Glad you brought this up.

Is there a 'norm' for the filter cycle? My controller allows one, two, or three cycles for one, two, or three hours per twenty-four hour period.

See lowering chlorine levels here.

So, there will never be CC to address? If there is CC how would it be corrected?

No personal hot tub reason other than I am going to change the water soon and thought I might shock the hell out of it, wait till the FC level won't kill the lawn, then drain and fill. You know, just in case.

Does anyone know if cranking up the FC will break down biofilms? And if so, to what level of FC is necessary?

Had that happen once to us after using Sea Klear. That is not to bad mother Sea Klear, I use it regularly with confidence, I feel it was an anomaly, but I digress. I used a plastic scraper to get as much goo out as possible then wiped up the remainder with a cleaner safe for spas (brand name escapes me). I let time finish the clean up. The spa seemed to fix itself after my half-baked clean up. Nitro, your advice in this forum is excellent and you are likely better suited than I to answer this question, but your post is missing the solution to Jim's question.

Look here

Stats: FC 2 PH 8 TA 80 CH 160 CYA 70 Borates an estimated 50 Temp 100 Pool Calculator 0.03 Is the PH of 8 a concern? Draining half the water would get the CYA correct, but I don't want to. Is there a compelling reason I should? There are no - and I mean no - issues with water quality, clarity, odor, FC drop, misc. build up, etc. The water is due for a change in two months.

Where were you yesterday! "...where did you find the blurb about 16 ounces of hydrogen peroxide removing 10 ppm FC?" Yeah, about that... the aforementioned whiskey might have played a role in my putting two entirely different paragraph together into what I wanted to read. Yes, it is 3%. Your basic drugstore variety. "...in 350 gallons, neutralizing 10 ppm FC requires around 7.1 fluid ounces of 3% hydrogen peroxide." That would be very close to what I experienced. Thanks for taking the time to sort through the math.

Hydrogen peroxide that is. I will spare you the whiskey induced excessive chlorine level story in my 325 gallon spa except to say the FC was 14 after 24 hours. I looked around this forum and found a blurb about hydrogen peroxide, lowering chlorine, 16 oz, and 10 FC drop. That was all I the persuasion I needed. I poured the 16 oz in the tub and poof! no FC. So, I added Clorox and added Clorox and added Clorox - no FC. Turns out it took 10 additional ounces of bleach to get back to an FC of 2. If memory serves, the 16 ounces of H2O2 offset 20 ounces of Clorox. Time to go relax in my experiment. I'll let you know if I have any skin left.

Thanks Dave. That is pretty much how I have been adding everything except muriatic acid. I am more comfortable pouring acid into the large, open area vs. spilling on the edge of the tub.

Thanks for the info. I guess there is no need to take a chance in ruining spa parts. It's easy enough to dilute and pour slowly.

By the exposure would be brief do you mean for humans? Or is there some detrimental effects on the spa?

And why wouldn't we just pour the bleach into the filter with the main pump on?

I can get a small, itchy rash on my right calf (yes, just on the right one) if I use MPS. It took a year to develop, but now if there is any trace of MPS in the tub the rash will re-emerge soon after soaking. I switched to the Dichlor/bleach with no ill effects. I shocked once the year with MPS and yep, the rash was back. I can't say if our rashes are the same. Mine is not clearly visible and would itch like crazy for a day although it was effectively relieved with cortisone cream. I took Chemgeek's advice and shock with bleach instead of MPS. I am thoroughly pleased with the use of bleach instead of N2/MPS. I was hesitant to use chlorine because some of the people that frequent my tub have issues with it. I have found that as long as the FC is <2 when we soak, no one has shown any reaction. I was also concerned with that chlorine smell: the one everyone relates to a public pool. No one, in the four months that I have be using chlorine, has smelled that I have been using this sanitation method. Shhh!

Thanks for the response Richard, Unfortunately I transferred the product into a sealed pail so I do not have the packaging. It must be the Multifunctional Shock as this is all they sell. I will test my CYA in a week, that will comfirm the product. I guess I could test for MPS, but that will have to wait since I just shocked with MPS. Which brings me to another question; how much Dupont 85% Oxone is correct for a weekly shock? I read MPS as a shock on many posts, but I don't see quantities. Konrad Update: My CYA is 70. This indicates your correctness. I just had the wife bring home Clorox. Do you feel this will correct my PH issue also?

The tub PH is rock solid at 7.3 TA 70 CH 200 (forgot to use soft water on last refill, duh!) CYA 45 Pool Calc. -0.31 I can get the PH to 7.6 just after running the jets with full air, but overnight we're right back to 7.3. I use Chemgeeks system except since I accidentally bought Dupont powdered chlorine (24%) from Lowes instead of MPS, I am using that instead of Clorox. Which, by the way, I now prefer. Any thoughts on raising and maintaining the PH level? The pool calculator indicates a PH of 7.6 would get me to -0.03.

I live north of Chicago and know what it is like to change water in the middle of winter. It is not as bad as it sounds. I do the spa flush first, then let it drain. Sometimes I help it along by bailing with my 5 gal Home Depot bucket, sometimes not. As the water is draining I clean what needs to be cleaned and use the old water to rinse. Remember, the water is 100F and no matter how cold it is outside your hands will stay warm. The fill water coming out of the spigot in this area is 55F in winter. There is no chance of that water freezing, even on a 0F day, in the time it takes to fill the water above where the heater can be used. I stressed the first time I did a complete water change on a really cold day, but no more. You will find out what a non-issue it is once you do it. Waiting for a mild day is always an option, but not a necessity.

At what point do you suppose admin will temporarily close the board to new members? When the regulars have all abandon this site?

Yes, that should have read PH up. Since adding enough Borax to get the ppm to 50 would send my PH through the roof, and I am somewhat against adding mounds of Borax and acid, and I am too cheap to spend $25 on a small bottle of 'borates', I guess I am liking my tub just as she sits.

Thanks for doing what you can.

Last check, which was last night, has my tub looking something like this: PH 7.6 CH 130 TA 90 CYA 40 100F - we soak for long periods as a cigar and a scotch take time to enjoy Ozone and N2 - MPS daily, used dichlor to shock, but now use this powdered chlorine stuff I accidentally purchased a while back. Water is two months old, crystal clear, no odor, and no foam. I know of and use the pool calculator. With no borate test strips yet, I can't plug that info in. I used Twenty Mule Team Borax at one point to get my TA up and now I gather I have some borates in there.