WaterBeast

>> I estimate that to get from your TA of 100 down to 80 in 380 gallons will take cumulatively about 10 teaspoons of dry acid, obviously not added all at once. Easy there. Small additions and retest. From experience I would probably only use maybe 3 tsp in my 280 gal spa to get the TA from 100 to 80, and that's with 50ppm boron.

>> I estimate that to get from your TA of 100 down to 80 in 380 gallons will take cumulatively about 10 teaspoons of dry acid, obviously not added all at once. Easy there. Small additions and retest. From experience I would probably only use maybe 3 tsp in my 280 gal spa to get the TA from 100 to 80, and that's with 50ppm boron.

Before you do 2 fills in one day on a well, you might ask if your friend has ever run his well 'out'. Some wells have less capacity than others. Once one is run out you may need to wait for that portion of the acquifer to recharge. This could be minutes, hours, or days.

Mine was mostly just greasy foam which could be removed with a sponge. By overfilling the tub before adding the flush, it made this more of a manual foam removal exercise than a spa shell cleaning exercise.

Buy a 1 lb container pH- (dry acid) for a spa or a 5 lb tub of pH- for a pool (more economical). You can get it most anywhere, hardware stores, pool and spa stores, etc. I inherited a couple bottles of liquid pH Down and found it more of a weak nuisance than it was worth. Muriatic acid is also a nuisance, but a much stronger and potentially hazardous nuisance as well. Stock up on some TA+ while you are at it. Acid additions to manage a high pH will eat up your TA, which you will also need to correct. When this makes sense, and your yin and yang are fighting for balance, read up on pH rise from aeration, and borates as a secondary pH buffers.

I would be using teaspoons of MPS (volume not weight of a different chemical) for shock. Teaspoons converts to weight based on the density of the granules you are using. I have little frame of reference, but I read that sugar is about 4.2g / teaspoon. I also have no idea of the chlorinating strength of the granules you have, but my brominating granules (Dichlor + Sodium Bromide) that I can also use as shock is not too far off the oxidizing strength of MPS. So based on the Scientific Wild Ass Guess (SWAG) that your chems aren't terribly different in potency than my chems, add 5g, wait 30 mins, test, and add more until complete. I may be off, but I'm not probably not wildly off. If you want to be more conservative, add less. It's probably more important to get the bromine level up sooner than later, and if it goes too high just wait for it to fall. Otherwise, wait for someone more educated to respond.

You want to maintain the CSI near 0 if possible, and no more than +0.5 or less than -0.5. Any more that 0.5 means that you have the potential for calcium scaling, any less than -0.5 can lead to corrosion. This is the threshold for when you should re-balance the water. Your CH is fine, I wouldn't raise it any higher. You can manipulate the TA and pH with the Pool Calculator to see how to bring your water into a little better balance. With practice I have found that I can maintain +/- 0.1 most of the time and never get past +/-= 0.5. Usually my pH is slowly climbing, so I play a slow pH-/TA+ addition game. The rash has me mystified. You might try a spa flush / decontamination routine to clear any resident biofilms that might be harboring somethign you are sensitive to. Also, consider using dichlor or bleach instead of MPS as a shock for a while. Reducing water temperature (heat induced rash), and making sure you aren't excessively blasting the same fleshy spot with a water jet also come to mind. I am generally reluctant to state 'allergic to chemical x (like bromine, chlorine, etc.) without careful testing but it is worth considering. A systematic process of elimination may be best. Keep us posted and I hope you get back to enjoying your spa soon. Also, I would normally recomend amputation and/or biologic sterilization, but you seem like a nice person so I'll hold off on that advice for now.

Limulus: Yes. Hilbilly: Too late. My skin turned blue-gray and is melting off me in nasty globs. More seriously, I was talking about leftover peroxide as an temporary alternative oxidizer not adding biguanide to a bromine spa. Otherwise I suppose could use it to bleach my hair to complement my new blue-gray complexion.

The CGCMS (not-yet-patented Chem Geek Chlorine Management System) using dichlor/bleach seems cheapest by a fair stretch. Bromine isn't bad, once you get in the groove with it, and I find it easy to use with a high degree of confidence - and I travel frequently. I like the additional safety factors with higher temp, higher pH, and potentially weeks worth of consistent auto-addition of sanitizer. It is definitely more expensive than chlorine, especailly using the Spa Frog system built into my spa. I'm now carefully buying in bulk off the internet which helps. No comment on Baqua, but I'm guessing somewhat expensive as it is not as broadly used. This looks viable, but I recommend doing your homework on the specifics and peculiarities of this system. Choose a system, get good with it, then optimize for cost. For example: buy 'pool' sized quantities vs. 'spa' sized quantities, get free shipping and no taxes on internet purchases, etc. for cost savings.

That's how I read it. I am still experimenting with the proper amount of MPS to add after use and weekly. It is clear to me that you need to consider multiple factors in your specific situation when shocking. I'm at 280 gallons, spa frog bromine+chlorine, and ozone, so I am seeing that a smaller amount of MPS goes a long way, and I can get well in excess of 10ppm bromine quickly if I add more than than 1 TBS of MPS at a time without re-testing. I'm thinking about rotating to bleach periodically just to change oxidizers and potentially gain a minor increase in efficacy. I also have a bunch of peroxide from the prior spa / spa owner that used Baqua that I am considering burning off as shock.

Excellent point. Sometimes what should be obvious is not so obvious. I'll fess up to being 'reasonably' but not 'very' good about not going in to the spa unshowered. Better to minimize the source of contaminants in the first place than to treat the contaminants.

OK, apologies to all the pools and spa store folks I may have wrongly maligned, however, I have the feeling that the people on this board tend to fall into the 'exceptional' category more than the 'typically encountered in the real world' category. Groblek: Hell, I have a background in computer science and the only thing that turned my light on was aggressive web-surfing research, and the Taylor manual - which I would have never seen if t weren't for this forum. The TA/pH thing pretty well had me mystified for a while. Limulus: CH 30 seems pretty low, CH is easily and inexpensively increased but not decreased, so you are in good shape there. Be sure to swirl lots (15s) between drop additions on the CH test, and make sure you reach real blue liquid, not just blue flakes suspended in a reddish liquid. For a while I was agitating the flakes back int solution, but this will give an incorrectly high reading.

If I may quote the illustrious ChemGeek, fountain of water chemistry knowledge (twice in two posts!): >> As for the quantity of chlorine vs. MPS needed to oxidize chemicals, two teaspoons of Dichlor is equivalent to four teaspoons of MPS and is equivalent to about 3 fluid ounces of 6% bleach. So long as you use equivalent quantities, you aren't really using "more" of any of these compounds unless you are comparing by volume, but given that bleach is mostly water, volume isn't really a valid basis for comparison.

If you are on bromine or chlorine, yes. <warning: I may not know what I am talking about here> Baqua - I have no idea, but I believe they use peroxide. I suspect peroxide would work as a shock too, just don't ask me how much. I would use a practical model of adding until I hit 10+ppm bromine (oxidizing power). <end warning> There is a recent post from ChemGeek translating MPS to 6% unscented bleach: >> As for the quantity of chlorine vs. MPS needed to oxidize chemicals, two teaspoons of Dichlor is equivalent to four teaspoons of MPS and is equivalent to about 3 fluid ounces of 6% bleach. So long as you use equivalent quantities, you aren't really using "more" of any of these compounds unless you are comparing by volume, but given that bleach is mostly water, volume isn't really a valid basis for comparison.

I missed the part where you started chlorine and switched to bromine. 2 MPS / person/use should be plenty, but you should be shocking with a similar amount weekly regardless of use. The MPS is somewhat acidic. I'm curious as to your Total Alkalinity and Calcium Hardness levels, but these won't cause greasy slime. 5 ppm bromine is fine. Are you maintaining 3-5ppm consistently? Are you using a straight sodium bromide tablet, or one that is mixed with a chlorine activator/oxidizer? I don't know much about the enzymes, I don't use them myself. They may not be a bad idea, but don't take the place of weekly shocking. I used the Zorbo (scum ball variant) for a while, they start to disintegrate over time no matter what you do. My attempts to clean them beyond squeezing them out seemed to accelerate the decomposition process. I would recommend using a commercial spa flush on your next refill (Spa System Flush, Swirl Away). I got out a lot of yellow greasy foam on my last flush and refill, and I manually removed it.