trouble maintaining bromine level with Spa Frog

[smartin737]

I am a relative newbie that received great advice on this site about buying my first hot tub in November 2010 (a used 2007 Hot Springs Vanguard).  I have really enjoyed it over the last 4 months and am attempting my first water change as we "speak".  Things have gone well (I think!), but I just want to make sure I'm not "under-thinking" the water chemical balance.   I am using the floating Spa Frog cartridge system with the bromine cartridge almost all the way open.  I usually leave it in the filter compartment to keep it out of the way.  I am also shocking it weekly with Leisure Time Renew. The tub is used about 3-4 times a week, usually by just me, but occasionally by other family members as well.   

My concern is this: when I use a test strip towards the end of the week, shortly before I use the shock, it shows little to no bromine in the water.  If I go ahead and add shock (that's what the Renew is, right?) then the levels are fine for a few days.  What am I doing wrong?  I thought the Spa Frog would keep that level up for me. 

Possible questions/concerns:
- should I not keep the floater in the filter well full time - maybe only when I am using the tub?  I assumed it would spread to where it needed to go since the water filters through there.
- am I shocking too much?  I don't want to hurt anything.  Or do I need to do it more often?
- In simple "Newbie" terms, what do I need to do to my water upon refilling it?  I don't have well water or particularly hard/soft water. 

Thanks in advance for the advice!

Sandy

[fdegree]

This is not written by me...I copied it from another very knowledgeable source.  I hope it helps.  My attempt to post the entire article failed...too many characters.  I'll put it into a couple of different posts.
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Bromine Sanitation
First, you need to establish a bromide reserve in the water. Bromine tablets can do it by themselves but it can take literally weeks until enough dissolve. Some people crush about 6 of them up and put them in the water on each water change to achieve this but it really is easier and cheaper to add a packet or two of sodium bromide. Bromine tablets contain both bromine and chlorine to oxidize the bromine into an active sanitizer. If you do not add the sodium bromide and just put in bromine tabs then you will be starting with a chlorine system until enough bromide dissolves in the water.

There are basically 2 ways to do a bromine system…2-step and 3-step.
2-Step System
In the 2-step system you add the sodium bromide to the water in the proper concentration, then add oxidizer on a regular basis (usually, chlorine, MPS, or ozone, or a combination of them) to oxidize the bromide ions into hypobromous acid, your active sanitizer. It's pretty easy but does require a bit of attention daily to maintain the bromine levels in the water. If you are using the 2-step bromine system (no tablets) then you would add your oxidizer on a regular basis to maintain the 4-6 ppm bromine level and shock it weekly with a larger amount of oxidizer to burn off the organics with the higher bromine levels that are created.
3-Step System
The 3-step system is identical to the 2-step system except for the addition of bromine tabs in a floater. This will help maintain a more constant bromine level in the water with less maintenance but otherwise there is no difference. The 3-step system costs more since the bromine tablets are the most expensive part of this equation. The dimethylhydantoin in the tablets seems to have a similar (but not identical) function in a bromine system as CYA does in a chlorine system. It tends to stabilize it but, like CYA, too much is not good. Not that much info is readily available on the effects of dimethylhydantion other than that it makes the bromine more difficult to destroy, a consideration if you ever want to switch over to a chlorine system. In a 3-step bromine system (with tabs in a floater) the tabs are what keeps the bromine levels at the 4-6 ppm range (they contain both bromine and chlorine) and you still need to shock weekly with additional oxidizer to burn off organics.

[fdegree]

Here is the rest of it...
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If you add sodium bromide to your water, and have an ozonator, you might be able to achieve the constant bromine level without the floater since the ozone is constantly oxidizing the bromide while it is on. However, you might deplete the bromide reserve quickly this way, leading to a shorter time between drain and refills. Also, ozone can cause bromates to form in your water. Bromates are a suspected carcinogen in drinking water.

You still need to superoxidize (shock), usually about once a week to destroy organics in the water whether you chose the 2-step or 3-step method. I prefer plain, unscented laundry bleach (5.25%) for shocking a bromine spa. 1-1/3 to 1-3/4 cups per 500 gallons is about right. If you use Ultra bleach (6%) then you need about 1 to 1-1/2 cups. You can also use 12.5% pool chlorine at half the ultra bleach dose. They are all sodium hypochlorite, just in different strengths. If you do not want to use a liquid shock you can also use: calcium hypochlorite granules (slow dissolving and will cause your calcium levels to rise), Lithium hypochlorite (very fast dissolving but very expensive, however my first choice for a granulated shock since it really has minimal impact on your water like the liquid does), or MPS--potassium monopersulfate, also called non chlorine shock (will lower your pH and TA and add sulfates to your water). There is no advantage to using dichlor (stabilized chlorine) for shocking a bromine system but it probably wouldn't hurt. CYA (stabilizer) does not stabilize bromine. You should shock weekly to get the bromine levels between 10 ppm and 20 ppm. Usually just above 10 ppm is sufficient. Leave the cover off and the filtration running until the bromine levels drop, usually a few hours to a day. Exposing the water to sunlight will help the bromine level drop faster.

Here is a step-by-step description:
1.   On each fill balance the water (adjust TA and pH. Add calcium if below 125 for acrylic spas or below 200 for plaster.) If you have metals in your water add a metal sequesterant.
2.   On each fill add sodium bromide to the water. (Follow manufacturer's directions on dosing. You will end up with about a 30 ppm concentration of sodium bromide.)
3.   Shock with your preferred oxidizer (chlorine or MPS) and turn on the ozone if you are using it. Your bromine levels should now be above 10 ppm. Wait until they drop below 10 ppm before entering the spa.
4.   If using the 3-step system, add your floater with bromine tabs and adjust it to maintain a 4-6 ppm bromine level. If using the 2-step system, add your preferred oxidizer as needed (and adjust your ozone) to maintain a 4-6 ppm bromine level.
5.   Shock weekly to burn off organics that collect in the water. (If you are using ozone and your bromine levels are staying at 4-6 ppm then you can shock less often.) Wait until the bromine level drops below 10 ppm before entering the spa.
6.   Test bromine and pH before entering spa each time. Test all water parameters (bromine, pH, TA, Calcium Hardness) weekly.
7.   Drain and refill about every 3-4 months.

[fdegree]

I have heard some folks say the test strips are not very accurate...they might get you in the ballpark, but are not sensitive enough to be precise.  I can tell you from my experience, I had trouble reading the different shades and trying to figure out what the reading truly was.  So, now I only the use the strips for determining if I am still over 10 ppm after shocking.  Instead of the strips I use the Taylor FAS-DPD Test Kit for Bromine...here is a link http://www.recsupply.com/eSource/ecom/eSource/Taylor_Complete_FAS-DPD_Test_Kit_-_Bromine_K-2106/i_1_0_/_BB210601.aspx ...you can probably find it a little cheaper if you search around.  But, in my opinion, it is well worth the money for precise measurements in water chemistry.  After receiving this kit, I compared it to the test strip and found the strips to be rather inaccurate.

I have heard other folks say they have trouble with the consistency of the spa frog.  To maintain the Bromine level between shocking, I use an adjustable floater...here is a link http://www.spadepot.com/shop/Floating-Bromine-Chlorine-Feeder-P609C43.aspx ...it takes a little getting use to in order to find the ideal setting.  But, it does work quite well and reduces the time required to keep checking on the Bromine levels.