Biofilm forms after circ pump fails for few days

[Mjb2000]

Newbie here and glad I found this forum. We have new spa (less than 1 month old) and had been using the Leisure Time Bromine System that came with it. While I was gone the, the 24 hr circ pump failed to operate for a few days and I returned to a green slimy hot tub. Since then, we've added about 8 oz 6% household bleach, balanced the water, and MPS shocked it twice.

It is still pea soup - but is not slimy.

[attachment=1:2tto74is]ImageUploadedByTapatalk1370788450.319168.jpg[/attachment:2tto74is]

oh perhaps I should have mentioned it foams too...

[attachment=0:2tto74is]ImageUploadedByTapatalk1370788509.038544.jpg[/attachment:2tto74is]

which does subside with the defoamer that came in the start up kit.

This forum has been a great chemistry refresher and I've ordered the 2106 kit as the test strips are pretty much useless, even with the app that reads them. Bromine levels don't seem to be read reliably by the strips - or the strip color develops very quickly - readings vary between 0 and 15.

Currently, I believe we have brought the pH and alkalinity down to 7.4 by adding both white vinegar (at first) then when this wasn't working fast enough 10% sulfuric acid (spa down). We had some residual solids in the floater, but I added three more bromine pucks to them.

And, last piece of info, we has just started WatersChoice, but as I said this is only a 1 month old spa and we've only added the 3 capfuls before we lost circ pump for a few days (which also kills the ozone generator).

Any suggestions or do we need to drain an fill?

 

[alanpaul]

Welcome MJB,

Have you read POOL SCHOOL, link-button at upper right?
If not, do so, and you'll have an idea what to do.

Required info will be volume in gallons, complete test results, and temperature.

Forum members, given the info above, will be able to heip you understand Pool School, and help you get your spa back to safe, clean and inviting!
Alan

 

[Mjb2000]

Thanks! That button isn't visible on the TapaTalk App.

The details:

350 gallons
100 degrees
Alkalinity 120
pH 8.4 (just tested, jumped up from last night when it was 7.6; added some ph minus and will retest)
Bromine 20
Hardness 200

 

[Mjb2000]

Update, waited 30 minutes and retested.

ALK 180
pH 8.2
BR 20
Hardness 200

Added more spa minus (10% sulfuric acid), will test again in 30 min.

 

[Mjb2000]

pH is now 7.4; in total about 16 oz of spa down (10% sulfuric acid) added over 14 hr period.

Alk 180
Hardness 200

Bromine is hard to read, the two different test strips come up with different readings. I've also heard high bromine/chlorine levels will affect test strip performance (for at least pH).

 

[chem geek]

Since the spa had biofilms form, I think you should decontaminate it, possibly using Spa System Flush or Ahh-Some. Superchlorination would be another option or you could do that in addition to using a flush product, but given that it was only a couple of days I think the flush will be sufficient.

 

[Mjb2000]

Thank you. I proceeded with a super chlorination, targeting about 100 ppm using dichlor (about 8 oz granuals). After about 4 hours, cycling air jets on and off, that seem to have gotten rid of a lot of the muck and minimal foam, but I've been battling to keep pH down and alkalinity up. And the test strips don't seem to work well when super-chlorinated. Running it now with the cover off to off gas a bit.

 

[chem geek]

Yeah, the test strips aren't that good even when levels are normal. You'll be happy with the K-2106 when it arrives.

Don't try to increase the TA level. Keep it lower if you find the pH tending to rise -- as low as 50 ppm TA if need be. If you do need to keep the TA that low to prevent the pH from rising, then you can add 50 ppm Borates (say, from boric acid) to help slow down the rate of pH rise.

 

[Mjb2000]

How much 20 mule team borax is 50 ppm in a 340 gal tub?

[attachment=0:ruz1z9g4]ImageUploadedByTapatalk1370830288.021073.jpg[/attachment:ruz1z9g4]

We are getting better, I ultimately had to add 32 oz of 10% sulfuric acid, then added more white vinegar.

Now the pH is 6.4
Alkalinity is 120
Hardness is 200
Bromine is 20

I was going to add a little baking soda to raise the pH. Does that sound right?

How long for the bromine levels to drop?

 

[TIMMAH]

run the jets to get the ph up since your TA is still too high. my tap water is 210 TA and it takes me about 2-4 hours of running the jets and adding acid to get the TA down to 60. add acid and run the jets with the air on until the ph comes back up to 7.8-8 then add more acid and wait for the ph to rise and do it again until you get your TA down.

what happens is when you add acid it drops the ph and when you run the jets with the air on the ph goes back. you don't want to lower your ph under 7.0 so you add just enough acid to drop it down to 7.0 and then the jets running with the air on will bring the ph back up and you keep doing it over and over until you get your TA to around 50-65 and your ph to 7.6. the lower your TA is the less acid you need to lower the ph. each time you add about 1/2 as much acid as the time before to get the same ph drop.

don't add the 20 mule team borax until you get your TA down. it will be hard to adjust after you add it.

 

[Mjb2000]

Thanks! Will getting the pH correct lower the bromine/chlorine concentrations? That's one relationship I trying to understand.

 

[chem geek]

How much 20 mule team borax is 50 ppm in a 340 gal tub?

After you get your TA down, you can use The Pool Calculator to calculate dosing. It will tell you to add 20 ounces weight (19 ounces volume) of borax and 9.5 ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) OR you can just add 13 ounces weight (14 ounces volume) of boric acid. You can see where to get boric acid in the Pool School article Recommended Pool Chemicals near the bottom under "Borate".

 

[chem geek]

Thanks! Will getting the pH correct lower the bromine/chlorine concentrations? That's one relationship I trying to understand.

No, changing the pH or other parameters won't change the bromine/chlorine concentration. That will only drop from 1) exposure to sunlight, 2) reacting with ammonia and organics from using the spa (i.e. bather load), 3) in the case of chlorine an ozonator will deplete chlorine or 4) adding a neutralizer such as hydrogen peroxide. In some cases, aerating the spa as you will be doing in the lowering TA process may outgas some bromine/chlorine.

Remember that if you have been using bromine so have a bromide bank, then an ozonator will create more bromine so you may not need to have your tab dispenser turned up as high.

 

[Mjb2000]

Thank you! We are looking much better....

[attachment=0:298utske]ImageUploadedByTapatalk1370923921.308928.jpg[/attachment:298utske]


The test strip results vary dramatically, depending on which brand I use - can't wait for the kit to arrive.

As for root cause, I determined a flaw in the balboa control logic used and not with the circ pump. This spa has a 24 hr circ pump/ozonator. When the water temperature is 3 degrees higher than the set point, the spa shuts down to avoid an over heat situation. So if you had recently used your spa and then turn the temperature way down (say you are going on vacation) - the circ pump and ozonator shut off until its within 3 degrees of the new temperature setpoint. With new insulated spas, this can take days. You then potentially have bioreactor waiting to brew!

There is a sleep mode that is suppose to keep the circ pump/ozonator working, it changes the 3 degree overheat "protection" to a 20 degree differential. A 104 F will not call for heat until temp drops below 84 F, but it will keep the circ pump/ozonator operating.

This brings up another question - if you are going out of town for a few weeks, what is the best way to defend against a nasty outbreak? I don't want to have to go through this again - is this where the chlorine/bromine salt systems (like ISIS) become worth it?

And maybe I'm not seeing it in "pool school" - is there a section that focuses on hot tubs given the differences between hot tub and pool care? Lots of great info there!

Thanks!

 

[chem geek]

I'm glad you figured out the problem and shared the solution for others to see.

In the Further Reading section of the Pool School as well as at the top of this Spa and Hot Tubs forum there are articles on How do I use Bromine in my spa (or pool)? and How do I use Chlorine in my Spa (or pool)?.

When away for more than one week, bromine is somewhat easier to manage since you can load up bromine tabs and if you have an ozonator than a bromide bank can continue to provide for bromine. With chlorine, you can elevate to a higher FC level and turn down the temperature, but that only works if you don't have an ozonator because ozone depletes chlorine. And yes, using a saltwater chlorine or bromine generator can help in this situation, though anything longer than one week is always a bit dicey unless you have experience with the setting needed for a stable level.

 

[Mjb2000]

Well, the water is still clear, but the sanitizer level is still well above 20 - even with the Taylor kit. When I super shocked with the dichlor, did I oxidize the sodium bromine beyond recovery? I can't turn off the ozone system without stopping the circ pump.

Do I need to just drain and start over?

 

[chem geek]

If you just want to lower the sanitizer level, you can add hydrogen peroxide. You add the same volume of 3% hydrogen peroxide as you would add of 6% bleach for lowering the FC by that amount. So to lower the bromine by 10 ppm (equivalent to 4.4 ppm FC) in 350 gallons, you'd add around 3.2 fluid ounces of 3% hydrogen peroxide.

 

[Mjb2000]

Well, I think I give up. I added two 16 oz bottles of 3% peroxide and the Taylor kit was reading over 30 ppm bromine 10 hours later.

Drain and refill...

 

[chem geek]

Wow. I wonder if the hydrogen peroxide doesn't work to reduce bromine. I know that it works with chlorine and I thought we've lowered bromine before with this technique. That's really too bad. The ozonator is probably adding to the bromine level, but perhaps the ozone got rid of the hydrogen peroxide -- I'll bet that is what happened. I probably should have had you turn off the circulation pump shortly after adding the hydrogen peroxide.

When you drain/refill, you should consider reducing your circulation pump on-time since the ozonator is tied to it.

 

[Mjb2000]

Unfortunately this control system doesn't allow any customization. All on or all off. Ozone, circ pump and heater are all tied together.

Maybe I'll switch to a Chlorine only system....