At what level is bromine too high to safely use spa?

[bbrock]

I shock my spa 1x/week w/ 10% bleach. I have a 300 gal. AG Aquaterra spa. Based on my calculations, I use 115 ml. In the warm months like now, I am keeping the water at 100 degrees. The problem I hate with shocking is that it raises the bromine level crazy high and renders the spa unusable for days. I try to burn it off by uncovering it and turning on the jets (without the aeration though; not sure if it would be better to add turn on the jet aeration to lower the bromine). Additionally, I remove the bromine floater (I use teh 3 step bromine system). It just doesn't seem to help get it lower than 10 at least for a couple of days. Sure, the jets are not on continuously. They just run for 15 min. cycles on high, then shift to low for 15 min. So, I have to keep going out to turn them back on.

The instructions in the 3 step bromine state to not use the spa until the bromine level is <10. I tried to research why and is it okay/safe to use w/ a high bromine level, but I could not find any posts about this. Before I had started managing it myself, at one time the level was crazy high and the pool guy said "don't worry it will just dry you out a little." Well, I did use it that time and yes, it definitely did dry out my skin, a lot. So, is that the only thing I risk using it w/ s high bromine level? For reference, I use a TF100 kit. I test the bromine in the spa w/ the OTO test. I just go off of what I have read here that a darker yellow is >10+ bromine, maybe up to 20. The color last night when I wanted to use it but didn't was a semi-dark yellow.

Lastly, I am not sure if I was reading this correctly, but I could have sworn I read a post in which Chem Geek had responded to someone that the FAS-DPD test could be used for bromine, but you must multiply by 2.25. Is that correct? For example, let's say the FAS-DPD used 10 drops, so that is 5 (10 * 0.5). Then 5 * 2.25 = 11.25. Could this test actually be used that way for bromine?

Tx for all the help.

 

[chem geek]

Bromine is not moderated in its strength by CYA so it's pretty darn strong which is why it will be unpleasant above 10 ppm. Now if you have been using bromine tabs then the DMH buildup from them might have some effect like CYA, though not as strong, but we don't have data on the exact relationship so we ignore it to be conservative. The high bromine level will oxidize skin, swimsuits, and hair faster and will outgas faster so smell more and may produce disinfection by-products faster.

If you want to lower the bromine level faster, you can use a reducing agent for that purpose. Standard dechlorinators do that such as sodium thiosulfate.

You are correct that you can use a chlorine test for bromine but must multiply your result by 2.25 to get bromine units. Also, you usually don't distinguish between FC and CC since even monobromamine reports as FC.

 

[bbrock]

Tx for all the great, insightful info. U surely know ur stuff .

Is the bromine level supposed to go sky high as much as it has after shocking w/ bleach?

Besides what u stated, any other options to bring it down?

What is the standard procedure for bringing down by "burning it off?" Not sure if I have been following it correctly.

So basically don't use after shocking until bromine is <10, which could be days?

Could I be using too much bleach to shock?

 

[chem geek]

The bromine will go up as much as you make it do so. If you don't want it to go up that high, then don't add so much bleach. The purpose of shocking with bleach is that bromine doesn't oxidize as many of the same chemicals as chlorine so to keep the water clear you usually need to add chlorine on occasion.

To lower bromine levels you can only 1) use a reducing agent including chlorine (bromine) neutralizers, 2) try and outgas it by running jets.

So yes, try using less bleach for your shocking. Also, 10 ppm bromine is equivalent to 4.4 ppm chlorine so it's not horrid, but again without the CYA it will probably be noticeable. I wouldn't call it unsafe. So you can either bear it or you can not shock with as much chlorine. Up to you. You can see if you can keep your water clear without using as much bleach to shock.

 

[bbrock]

Rt on. Tx. I'll try using less bleach to shock and less how that does.

This AM's Br level using OTO was 10+ (only slightly darker than the 5, aka 10 Br, color block), but with the FAS-DPD test x2.25 it was 9. I think I did it right. It took 8 gtt of reagent to get the 10 ml sample clear. 8 x0.5 = 4 x2.25 = 9. So pretty close b/w the two test. Bu,t then again, reading the OTO is relatively subjective. Hence, maybe the color was closer to 5 chlorine/10 Br.