5 days of "burn out"???

[steveinaz]

Ok, pool is filled start-up completed. I have a question. The PB gave me 5 bags of Bioguard "Burn out" that they want me to add 1 bag each day for 5 days. I put the first bag in last night and my Chlorine was off the charts (I stopped at 15 drops=15ppm).

Is this necessary? Why would I need to "shock" my pool 5 days in a row?

[chem geek]

Bioguard "Burn Out 35" is 29% Lithium Hypochlorite by weight while "Burn Out Extreme" is 47% Calcium Hypochlorite (so, Cal-Hypo). If your PB is having you use the latter (and 1 pound bags sounds like the latter), then this is a way of getting both chlorine and calcium into your pool, but normally you would add large amounts of calcium with Calcium Chloride. I don't know why the PB is having you add so much chlorine.

1 pound in your 12,000 gallon pool will add about 5 ppm FC so I'm not sure why your FC is already > 15 ppm (it also adds 3.4 ppm of CH). By the way, the Taylor FAS-DPD tester has 1 drop = 0.2 ppm when using the 25 ml sample while 1 drop = 0.5 ppm when using the 10 ml sample. Are you using the 25 ml sample? If so, then 5 ppm FC would be 25 drops and would explain what you are seeing. When you expect the chlorine level to be high, you can use the 10 ml sample in which case 5 ppm FC would be 10 drops.

My guess is that the PB is expecting there to be a lot of initial chlorine demand, but if you added 5 bags (5 pounds) you would end up adding 24 ppm FC. I doubt that the sun this time of year is burning off your chlorine that fast or that you have that much chlorine demand. Perhaps you would lose 1/4th of your FC level each day due to sunlight -- during the peak of summer it would be closer to 1/2.

Richard

[steveinaz]

THANKS! I was thinking 1 drop=1ppm, my fault. I was using the 25ml sample. It is the 47% mixture. This makes sense then. I do need to raise calcium level.

Thanks again

[chem geek]

Well, Burn-Out Extreme (Cal-Hypo) isn't a very effective way of adding a LOT of calcium since even after five 1-pound bags you will only raise your CH by 17 ppm. Adding Calcium Chloride will get your CH up as well and is probably a lot less expensive. I remember buying a 50-pound container after I did a half drain and refill equivalent using winter rains, so needed to get my CH back up. You should probably test your CH level to see what it is. If you pool is new plaster or re-plastered, then calcium hydroxide will get into the water from the plaster as the plaster cures. That will add calcium to your pool and will raise the pH so expect to be adding lots of acid over the next few months to maintain the pH. At any rate, you probably want to do what your pool builder says regarding calcium levels assuming you are under some sort of warranty for this job.

So, I agree that using Cal-Hypo makes sense as your chlorine source while you are needing to raise the CH, but if you need to raise it quickly then adding calcium chloride is more cost-effective. In other words, I would do both -- use calcium chloride for the bulk of the increase you need (remembering that more calcium will be coming from your plaster during curing) and use Cal-Hypo for chlorine until the CH is where you want it.

Richard

[steveinaz]

My fill water calcium (from the tap) was 180ppm. I would imagine I want it around 200-400 for a plaster pool right?

[chem geek]

Yes, you will probably shoot for around 300 ppm CH, but you are already at 180 from your tap water (are you sure about that? you tested it with the CH test? the "hardness" number from water companies isn't the same as CH since it includes magnesium as well as calcium). Since the calcium level should rise if the plaster is new, your PB's advice of just using Cal-Hypo for chlorine is probably good enough for now. If you're at about 200 ppm CH, you're in pretty good shape and can just let the plaster plus your Cal-Hypo get you up higher.

My water isn't nearly as "hard" so that's why I thought you'd have to use Calcium Chloride to get your CH up faster, but you don't have to do that with your "already high CH" water.

Richard