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Thank you chem geek for the detailed answers. Really appreciate you digging into the details. A few more questions have come up for me as we've been using the tub which has been working great with the dichlor-bleach method. 1) What are you recommendations regarding how and how often to clean the filter? I have found some information here but methods seem to vary significantly from light spraying to monthly soaking. I'm thinking regardless, its not a bad idea to buy a second so that when you are cleaning one, the other can be in the tub. 2) How do I know when I need to perform a water change? The water clarity has been great in the tub though I suspect visual inspections isn't the way to determine.

Chem Geek - Thanks for all the great information on this site! We recently just got our first hot tub and I've been following your dichlor-then-bleach method. We have a 355 gallon spa set at 101 degrees. No ozonator. Have the Taylor k-2006 kit. Raised the CYA level to approximately 30ppm by measurement of dichlor added. Typical use is 1-2 adults every 2 days or so with addition of 2 kids (4 total) on weekends. A few points that I wanted to clarify as well as a few questions - 1) 1/2 a cup is approximately 4 ounces so using 8.25% bleach - if we have 4 people soaking for 1 total hour, I would need approximately 2 cups of 8.25% bleach to have enough chlorine to oxidize the soak as well as some residual the next day? 2) 50ppm borates (in the form of granular boric acid) according to PoolMath is 14 oz by weight or 15 oz by volume. So by volume would be approximately 2 cups boric acid. 3) What is the CYA level that you recommend these days? In the beginning of this thread it looked like 20-30 ppm but I've read a few threads where I think either you or waterbear have recommended slightly higher levels 30-40ppm from years of experience with the dichlor-bleach method. 4) Is there a FC level that would harm the tub? From my reading of this forum, for those that "shock", they bring FC to approximately 9-10ppm. I'm planning to be away for 7 days in 2 months and am trying to determine what level of FC I want to raise the spa to prior to leaving. I've calculated my chlorine demand (though did not do it after initial fill as you suggested - missed a step!) to be approximately 40% at this point in time. 5) What is your recommended routine for filter cleaning/maintenance? I haven't found much discussion about this issue here. Thanks again for your time!

Got it! It makes sense that some of the initial 19ppm of FC from the 2 tablespoons of Dichlor must have gotten used up by the time I tested the water with the Taylor 2006 kit which gave me that 5.2ppm measurement that I mentioned. So my plan is to measure the FC before getting in the tub today. I will then add dichlor to get to 5ppm FC. After about 30-60 minutes of soaking, I will measure the FC again. If the FC after soak is 0, I will start with adding slightly more dichlor the next time (6-7ppm), if there is some residual FC, I will add slightly less next time. Since I have already added 19 ppm FC and 17 ppm CYA initially, it should not take long for me to reach 20-30 ppm of CYA at which point I can switch to bleach instead of the dichlor. 1) Does this all sound about right? 2) At the beginning, should I also be regularly checking pH or any of the other items for water balance (TA, CH etc) to make sure they are staying in check? If this is all correct, I'll move on to targeting and working on borates!

Thanks Chem Geek for your analysis! Still a little confused about when I can switch to bleach. My first 2tbs of dichlor yielded a calculated FC of 5.2PPM. The guide states "For every 10 ppm of Dichlor you add to your tub, you add 9 ppm CYA". Does this mean I've added only about 4.5ppm CYA at this point? Part of my confusion is that I don't understand how that fits in with the "Effects of adding chemicals" calculator in the Pool Calculator which tells me that since 2 tbs is 1 ounce and by the pool calculator, it tells me that 1 ounce of dichlor should raise FC by 19 and raise CYA by 17.

Hello - Thanks to everyone who has contributed to these forums. I've been reading and re-reading, particularly Nitro's guides and here is where I am at. I have a 220 gallon hot tub and am using the Taylor 2006 kit. 1) I initially cleaned the pipes (Swirl Away) and then decontaminated. 2) I brought the CH from 50 to 150PPM. 3) I brought the TA from 40 to 80PPM. 4) Checking the pH after the TA settled, I got a pH of approx 7.7. This is where I started getting confused via Nitro's "sanitation" instructions. 1) Checked my FC level and got 0. 2) Using my hot-tub recommended instructions, I added approx 2tbs of dichlor to initial "shock" and calculated a FC of 5.2PPM after 8 hours of agitation. Agitation occured with the top off on a relatively sunny day. I guess my basic question is - what now? Via my reading, it looks like I should try to immediately raise the FC to approximately 10PPM prior to first use. My understanding from the reading is that I want to reach a total FC over the next several days of approx 34 to reach a CYA level between 20-30 however, I'm a bit confused on how to proceed the next several days. 1) Can I start using the tub while the remainder of the calculations are occuring? 2) How do I figure out exactly how much additional FC I am adding on a daily basis? Should I assume in this case that adding 2tbsp of dichlor will add approimately 5PPM of FC as it did the very first time and continue on a daily basis until I reach an additive total of 30PPM FC? The example that Nitro gives: "For example: On one day you test your FC and it's 1 ppm. You'll then add 5 ppm FC to bring it to 6. The next day you test FC and it's 3. You then add 3 ppm FC." This is confusing to me - perhaps someone can just clarify and all this will make sense to me? Sorry about such a long post! I'm excited to start using the tub but want to make sure that I do everything as right as possible! David

Thanks Chem Geek! I ran Swirl Away through the system yesterday evening and let it sit overnight. Some bubbles at the top but no real "goop" or anything else to speak of! Will continue the superchorination today and hopefully post my water results for some help in continuing with my water chemistry!

Hi - I'm new to this forum and hot tubs in general and was hoping for additional clarification on a question that had been asked but never really answered I would like to follow Nitro's decontamination regimen since I just came into possession of a used hot tub. The instructions has Swirl Away and Shock as two separate fill and drains. Is there a reason why I can not fill the tub, run the Swirl Away overnight, super shock the next day and then drain completely? I understand why you can not Shock first as that would interfere with the enzymatic action of Swirl Away not why would it not work the other way around? I apologize in advance if this has been answered elsewhere. Thanks!