Dichlor/bleach Questions

[HuMan123]

Hi,

I have some questions pertaining to my setup to switch over from MPS/Nature2 to dichlor bleach method.

My tub is a new Hot Springs Jetsetter of 225 gallons. It has 24/7 ozone and Nature2 in with Tri-X filters. It is on it's 2nd fill which was done 24 days ago. I have only used dichlor I think twice in this fill and have kept MPS at maintained levels. I just took readings with my Taylor K2006.

PH - 7.4

FC - 0 (guessing a bit because I use MPS)

CYA - <30 (filled comparator tube to top and could still see dot) (Low after 24 days because of minimal dichlor usage???)

CH - 100

TA - 65

MPS - Ok reading on MPS dip stick

Can I go to dichlor/bleach even though it is not a fresh fill because my CYA is lower than 30? If so, should I raise it to at least 30 before starting?

Other scenarios/questions. I was given several Nature 2 sticks and 2 big jugs of Silk Balance that I have been using. I would like to continue to use these if possible since I have them.

Big question is do I need to use borates it I continue to use Silk Balance which I think has some buffer properties???

Any and all advice is greatly appreciated as I want to move over to this method quickly to test MPS sensitivity theory.

My dichlor I have now is Spaguard Enhanced Shock which is only 58.2% dichlor so any math whiz types out there to help me convert to Pool Calculator readings?

Thanks in advance and I am off to the store to buy some Chlorox bleach in anticipation of starting.

[chem geek]

You can just use Dichlor initially to build up more CYA and then switch to bleach after that. As for the borates, you'd lower your TA first to around 50 ppm and I'd think you'd still need them since I don't think Silk Balance is as strong a pH buffer -- then again, you can just see for yourself but be very careful since you don't want the pH going up way too high and causing scaling (depending on your CH level -- with the lower TA, the risk for scaling is less).

Just divide the Pool Calculator amount of Dichlor by 0.582 to get the amount of Enhanced Shock that is needed, but since I don't know for sure what else is in the Enhanced Shock, I can't tell you for sure what it will do.

Note that with an ozonator, the chlorine demand will be lower during bather load, but in between soaks with no bather load (so if not soaking every day or two), then the chlorine demand will be higher so you'll need to add bleach more frequently. In other words, with an ozonator, using the spa every day or so works well, but if you don't soak frequently then an ozonator is not as helpful and actually makes chlorine maintenance more troublesome (more frequent dosing required).

[HuMan123]

Thank you for the response. I have a couple of follow up questions.

Nitro's writeup says to lower TA to ~80ppm - is 50PPM new improved guidelines learned over time? Mine is at 65 and I am asking to see if I should try starting at this point and if so, what should I watch for to see if 65 TA is too high?

Also, the writeup says to add 50 ppm of borates. To accomplish this using the pool calculator do I assume the level is zero now to have the calculator tell me how much to put in? Is this a onetime per fill add of borates or do I need to measure somehow and keep adding?

Silk Balance is marketed to keep PH/etc from wandering so I may give it a try and watch PH closely. My experience so far with it is that my PH, CH, etc are staying stable so not sure if it is the SB doing it or I just have TA/PH very balanced from initial bringing down/airating procedure.

Thanks,

[chem geek]

Yes, a lower of TA of 50 ppm has been found to be better for most spas, especially when there is aeration from jets. As for your TA of 65 ppm, why don't you just see how the pH behaves. If it tends to rise too quickly over time, then try lowering the TA to 50 ppm and see if that helps.

The borates are a one-time fill after each water change; it does not break down. Yes, assume you have zero now since borates are not in tap water (or rain water, etc.). You can add the borates either with boric acid (easier because it doesn't require much pH adjustment after addition) or 20 Mule Team Borax with acid (Muriatic Acid or dry acid). If doing the latter, add partial doses back and forth to not have the pH swing so much with each addition.

Yes, you can just see if the lower TA and use of Silk Balance are enough to keep your pH stable. As for CH, that won't change unless you add something to the water with calcium in it, such as using Cal-Hypo as a chlorine source (usually not a good idea, especially for spas, since you want to avoid scaling from high CH).

[HuMan123]

Well I have made the change over to bleach and thank you for all your help Richard and others who post! I did find some interesting things that did not align with my expectations.

CYA - level was <30ppm as I could still see the dot with my Taylor test kit full to the top of solution, I added 1.5 Tbsp of 58.2% (dichlor) "Spaguard Enhanced Shock" and my 2 readings on different days show CYA @ 47ppm which does not make sense to the formulas I have read regarding CYA from dichlor. The FC jumped from zero to 14ppm so how could CYA jump >27ppm (30+27)?

Using the Clorox 8.25% on my 225 gallon Jetsetter tub with 24/7 ozone I appear to be seeing higher that published FC usage by ozone. (possibly because ozone on Jetsetter is the same model HotSprings uses on much larger tubs???) My early numbers are usage of 60% or slightly higher...have had the cover off a lot and jets on.

Early numbers on my "per hour" bather load is using 2oz for 24 hour period per bather hour. These are very early numbers as I have just begun using bleach. Alk is @ 50-55 and CH is 100.

I have not used the boric acid (ordered from "Duda Diesel which has excellent shipping and pricing) because I wanted to see if the Silk Blance I am using would buffer PH since it is marketed as a buffer. So far the PH is holding or just slightly lowering???? Which is the opposite of what I was expecting? Starting PH was just on the light side of 7.4 and now is just heavy side of 7.2PH.

Just some feedback for others to compare and I will continue to update my findings.

Any and all comments are welcome.

[chem geek]

The amount of Dichlor you added is consistent with 14 ppm FC and 12-13 ppm CYA. The CYA test is subjective and hard to get within +/- 10 ppm. The standard lighting conditions for it are when you stand outside with your back to the sun where your body shades the tube you hold in front of you looking down into it. This is strong indirect lighting. You were probably not far from 30 ppm and got to roughly 45 ppm or so.

Yes, it does sound like your ozonator is more powerful. That's good if you plan to use the tub every day, but not so good if you only plan to use it only on weekends. Too bad you don't have a way of turning it on and off.

As for the pH, recognize that Dichlor is net acidic when accounting for chlorine usage/consumption. If there were no carbon dioxide outgassing, then 14 ppm FC from Dichlor that then got used up would drop the pH from 7.5 to 7.0 so clearly you've got outgassing and your pH will tend to rise when you are just using bleach. The borates will help buffer the pH. If you had 50 ppm in there the pH from the Dichlor would have dropped from 7.5 to 7.1, but you'll really see the borate benefit slowing down the rate of pH rise since the borates are a strong pH buffer as the pH gets higher.