Slight mod to vermonter method

[knightcap]

I'm new here, and new to hot tubs.  I've had my tub since Nov 06, and have learned a lot here -- thanks!  I am using vermonter's method: a tsp of diclor for each user after each use, with a shock about weekly of about 2 tbs diclor.  I use the tub about 3-4 times per week, usually only one or two people.  So this is about 6-8 tsp of diclor per week, plus the weekly shock.

I was wondering about this: my ph tends to drift down (I add ph up evey week), and I thought diclor could cause this.  Plus, that's a lot of TDS I'm adding.  Does anybody have an opinion on using liquid bleach as a weekly shock?  I know bleach doesn't last long in hot water, but for shocking it doesn't need to last long.  I was thinking about continuing to use diclor after each use, but once a week use about a quarter cup of 5.25% bleach -- I'll compute the dose to get me up to 10-12 ppm.

Does anyone have experience, or an opinion, with using bleach to shock?  The goal is to cut my diclor use about in half, in order to have less impact on ph and TDS.

[Spiderman]

I might be wrong, but I would think bleach would be a little hard on the plumbing, etc.  

[windsurfdog]

knight,

What is your extrapolated combined chlorine reading before you shock?  I ask this because you may be adding too much chlorine when you do shock.  If your combined chlorine figures out to .5 ppm or less, you would only have to add enough dichlor to raise your ppm to 5 or so to achieve the breakpoint.  By using 62% active chlorine dichlor in my 450 gallon tub, I can raise ppm to 5 with a little under 4 tsp.  This isn't a big difference from your 2 tbsp. (6 tsp.) but is something to consider.  Also, you might monitor your combined chlorine a little closer before your scheduled shock...if it's already good and low as a result of lack of tub use or ozone and/or mineral usage, you may want to forgo a shock altogether.  Worth consdering anyway...

[tony]

Bleach will certainly work and it will raise your pH.  Be sure to use straight bleach, not scented, etc.  The problem with bleach other than the high pH (13) is the method of delivery.  Spilling it on your spa, chlothing, etc can be problematic which is most likely why most spa manufacturers instruct against using it.

[Chas]

I shock once per month and have good results.

I have recently switched to Brilliance (I had a bunch of it at home and like the ease and the pleasant odor) so I'm shocking with MPS right now - and that is once per week.

But on Dichlor - the Vermonter method - I shock once a month or after a group exits the tub.

 8-)

[Chad]

knightcap,

At what level do you keep your alkalinity?
Experiment with keeping it at different levels until pH starts to stabalize for longer periods of time.

[Brewman]

Bleach can be corrosive to stainless steel- I have to watch that in my beer brewing, since bleach is often used as a sanitizer.  Some spas have stainless steel trim around the jets.  Not sure if the relatively low concentration of bleach in the spa would cause any corrosion, though.
Just something to consider.

[knightcap]

a couple comments;

I'm not sure if bleach would be hard on the plumbing or corrosive -- isn't 5-10 ppm chlorine the same no matter the source?

Alk -- usually, mine is bout 100 or 120.  Sometimes drifts down to 80-90.  Maybe I should get it up a little higher to try to stabilize my ph.

combined chlorine -- I don't know mine.  I use a simple test kit (I think its an OTO test?).  I add five drops to the vial, and check the color -- basically different shades of yellow.  I think it is giving me total chlorine -- so I don't have a break out of free and combined.

I shock about weekly, even though I don't know my CC level, mainly for the super-sanitizing effect.  For this same reason, I shock with dichlor, not MPS.  This is what led me to start thinking about shocking with bleach -- to get the supersanitizing effect of 5-10 ppm chlorine without bringing up my TDS and dragging down my ph.

Thanks for the comments and help!

[Bill_Stevenson]

"my ph tends to drift down (I add ph up evey week), and I thought diclor could cause this.  Plus, that's a lot of TDS I'm adding...."  

The pH of dichlor is roughly 6.5, but your body sweat and deodorant etc. probably has more to do with the drift than the small amount of dichlor you are using.  Your perception that you are adding a lot of TDS from the amount of dichlor you are adding is not really all that much. You can verify the actual effect by testing for TDS both before and after dichlor addition.  It should prove almost unmeasurable.  Also, I am assuming that your quantities added are based on measurement of the free chlorine taken approximately 15 minutes after the addition.  What the Vermonter recommends is that the free chlorine be in the 3-5 ppm range (if memory serves), rather than an amount of dichlor.  

Regards,

Bill

[Reese]

I agree with Bill -- your pH drift is more likely due to other factors than small dichlor doses.  Using household bleach instead of dichlor will slow the build-up of CYA, but I'm not so sure about TDS.  I seem to recall that bleach has a lot of dissolved salts.  If you are comfortable with the handling and safety issues, given your low pH problems, bleach shocks sound like a good idea.  I also think the shelf life of bleach is relatively short, so watch the potency -- inadequate shocks actually add to combined chlorine.

Raising TA could help buffer pH changes.  Since you are seeing drift down, try running at the higher end of the range. If your "pH Up" is sodium carbonate, consider using baking soda (bicarbonate) instead.  It will raise TA, along with a lesser rise in pH.

[Chad]

I agree with Bill -- your pH drift is more likely due to other factors than small dichlor doses.  Using household bleach instead of dichlor will slow the build-up of CYA, but I'm not so sure about TDS.  I seem to recall that bleach has a lot of dissolved salts.  If you are comfortable with the handling and safety issues, given your low pH problems, bleach shocks sound like a good idea.  I also think the shelf life of bleach is relatively short, so watch the potency -- inadequate shocks actually add to combined chlorine.

Raising TA could help buffer pH changes.  Since you are seeing drift down, try running at the higher end of the range. If your "pH Up" is sodium carbonate, consider using baking soda (bicarbonate) instead.  It will raise TA, along with a lesser rise in pH.

8-)

[CapMorgan]

There is not really that much of a difference in TDS between bleach and Dichlor.

Bleach = 1.6 TDS
Dichlor= 1.8 TDS

If you decide to use bleach for shocking premix it with water before pouring it into the tub.

CapMorgan

[tony]

There is not really that much of a difference in TDS between bleach and Dichlor.

Bleach = 1.6 TDS
Dichlor= 1.8 TDS

If you decide to use bleach for shocking premix it with water before pouring it into the tub.

CapMorgan

Premixing is really the way to add bleach to your spa.  Good suggestion.  As Reese mentioned, the advantage of using bleach is lack of CYA more than TDS.

[Chas]

Bleach has a pH of close to 13. So most folks have to add bleach and then immediately add some sort of acid.

This, to me, makes it a poor choice. You still end up having to drain the tub about every four months, and you have added every bit as much or more TDS.

 8-)

[hottubdan]

I've always understood if you drain every 4 months or so, TDS is not a problem.