We're running our hot tub with sodium bromide and recently converted from a bromine generator to brominating tablets (floater). The first two heater elements (replaced about 2 weeks apart) were corroded very likely due to low calcium levels (11ppm). Once we brought the Ca level back to 125ppm, we've had regular water tests with good results. Now, we've had a 3rd heater element go?? What might be causing this (if not a chemical issue). We've been advised to empty our tub, refill it and wait for the dissolving brominating tablets to bring the bromine level to 3-5ppm -- I'm not convinced that will help!
4th heater element in 2 months!!
- Thread starter moniquejoyce56
- Start date
- May 23, 2015
- 24,417
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
What's your pH and TA? Brominating tablets are often very acidic and will decrease TA to the point of causing the pH to crash. Acidic water with a pH of less than 7 will cause the corrosion of a heater element. Also, you should have the heater replaced with a TITANIUM element. Many hot tubs are constructed with Incoloy (nickel-bearing stainless steel) heaters which are cheaper than titanium but last half as long and are subject to corrosion. A titanium heater will last a lot longer even in more corrosive water.
Also, calcium levels will not prevent corrosion of the heater. All heaters corrode slowly. Calcium might possibly (there's some significant debate about this) slow down the rate of corrosion a little bit, but it's probably not noticeable enough. You need at least 125ppm CH to keep your water from getting foamy and having CH up to 200ppm wouldn't be a problem. Much higher than that and then you really need to be careful about your water chemistry and saturation index because the heater will start to develop calcium scale which will cause it to overheat and burn out.
Also, calcium levels will not prevent corrosion of the heater. All heaters corrode slowly. Calcium might possibly (there's some significant debate about this) slow down the rate of corrosion a little bit, but it's probably not noticeable enough. You need at least 125ppm CH to keep your water from getting foamy and having CH up to 200ppm wouldn't be a problem. Much higher than that and then you really need to be careful about your water chemistry and saturation index because the heater will start to develop calcium scale which will cause it to overheat and burn out.
My pH was 7.6 yesterday but had been in the 8.2-8.6 range in the last month. TA reading is 80 but had been in the 155-125ppm range.
I did add 2 bromine tablets directly into the skimmer last week + added some pH- which explains the changes in the pH + TA readings.
I need to add some TA+ to get my level back up.
The new heater element is made of titanium.
I recently disconnected my bromine generator (relying on the brominating tablets) as well as disconnected my ozonator ( it sure it was doing anything anyway!).
I did add 2 bromine tablets directly into the skimmer last week + added some pH- which explains the changes in the pH + TA readings.
I need to add some TA+ to get my level back up.
The new heater element is made of titanium.
I recently disconnected my bromine generator (relying on the brominating tablets) as well as disconnected my ozonator ( it sure it was doing anything anyway!).
- May 23, 2015
- 24,417
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Yeah, you definitely do not want to add chemicals into the skimmer, that's very bad for the heater. The dry chemicals will create a very acidic "stew" of water that will directly hit the elements and damage it. Also, dry acid is pretty bad. It's sodium bisulfate and leaves sulfates behind in the water. Sulfates can be really bad for steels (especially the steel in an Incoloy heater) as it will enhance crevice and pitting corrosion. I know people don't like to use liquid muriatic acid, but it is better for your tub hardware in the long run and can be more easily diluted. I would recommend you switch to MA for pH lower.
If you keep your TA at those really high levels, then your tub is always going to have pH rise problems. pH rise is directly correlated to the outgassing of CO2 from the water and you carbonate alkalinity is contributing to that. With brominating tablets that are acidic, I would consider only going as high as 100ppm TA and then carefully monitor your pH and TA over time. 150ppm TA is way too high and if you add that plus 150ppm CH, you're going to get calcium scaling all over the tub.
Please see this sticky for how to properly use bromine in a hot tub - How do I use Bromine in my spa (or pool)?)
If you keep your TA at those really high levels, then your tub is always going to have pH rise problems. pH rise is directly correlated to the outgassing of CO2 from the water and you carbonate alkalinity is contributing to that. With brominating tablets that are acidic, I would consider only going as high as 100ppm TA and then carefully monitor your pH and TA over time. 150ppm TA is way too high and if you add that plus 150ppm CH, you're going to get calcium scaling all over the tub.
Please see this sticky for how to properly use bromine in a hot tub - How do I use Bromine in my spa (or pool)?)
