Mustard Algae and Sodium Bromide (Long)

HI guys, I have been trying to eliminate mustard algae for abotu a week now and am not sure if i am doign it right. Brief history...

30ft above ground pool and i have been using the "pool solutions" chemicals for 2 full seasons and this is my third...and my first with mustard algae.

I kept the FC level above 10 (with a CYA of only about 30) for a solid week and then on satuday I added 8oz of sodium bromide. Sunday I saw a hint of it so I added more clorox and 4oz of sodium bromide. Monday was a hot day and the first real use the pool got, so last night I added more clorox as I did this mornign when I saw the FC was falling down to around 5. Tonight I get home from work after it poured for 4 hours and I had zero FC and the mustard algae was back...(filter has been running 24/7 for more than a week)

So I thru in 2 gallons of clorox immediately and thru a triclor tab in the strainer (which I have been using some the past 2 weeks to bring the CYA up) I just recieved my 233 refill so I will read my CYA again tomorrow.

SO....after 2 full years of hardly needing to do anything except add clorox to the pool I am struggling a bit.

I see that of late most people are suggesting polyquat as opposed to sodium bromide?

HELP!!!!!

The sodium bromide creates a bromide bank in the pool that you need to activate by shocking with chlorine after adding it. You will then temporarily have a bromine pool. If I am not mistaken bromamines will form and the algae will consume them and be killed. If you just add the bromine and don't shock the pool it really doesn't work. Keep shocking and it should take care of the mustard. The bromine can create a large chorine demand for a while. that is normal. Just keep getting the chlorine in there at shock levels until the pool clears and the FC is holding. CYA will do you no good as long as the pool has active bromine in it since bromine isn't stabilized by CYA.

Thanks Evan. I will keep going with this then. I brought the FC level up over 10 last night and this morning I added another 8oz of SB to the pool and added ALOT(3 gallons) of clorox to shock it. I am gone during the day but I would guess that when I get home the levels will still be above 10. And I will keep it this way for a few days. I vacuumed to wasted this morning as well, to lower the levels of the pool from rain, and also to get the mustard algae out of the pool.

If this does not do the trick I am out of sodium bromide...is there another way to atttack this that you would recommend? Polyquat?

The Sodium bromide has created a bromine bank in your water. Every time you shock with chlorine the chorine is 'converted' into bromine until the bank is exhausted. Just keep shocking. This is why your chlorine is not holding. It is reactivating the bromine. I would be careful about overdosing on the sodium bromide because it can create a VERY LARGE chlorine demand. Just give it time to work and keep shocking unitl the algae is gone and your chlorine is holding. (and don't forget to BRUSH, BRUSH, BRUSH!)

BTW, this is not very different then running a spa on sodium bromide...sodium bromide is added to the water and then chlorine (usually bleach, cal hypo, or dichlor) is added to activate it. When the bromine level drops you add more CHLORINE to reactive the bromine!

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Originally Posted by waterbear

The Sodium bromide has created a bromine bank in your water. Every time you shock with chlorine the chorine is 'converted' into bromine until the bank is exhausted. Just keep shocking. This is why your chlorine is not holding. It is reactivating the bromine. I would be careful about overdosing on the sodium bromide because it can create a VERY LARGE chlorine demand. Just give it time to work and keep shocking unitl the algae is gone and your chlorine is holding. (and don't forget to BRUSH, BRUSH, BRUSH!)

BTW, this is not very different then running a spa on sodium bromide...sodium bromide is added to the water and then chlorine (usually bleach, cal hypo, or dichlor) is added to activate it. When the bromine level drops you add more CHLORINE to reactive the bromine!

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Thanks...I am going to keep hitting it with chlorine..but yes it is gobbling it up.:eek: I would say i am going to be going thru 25 liters over 24hours for the second straight day. But i see no signs of the algae in the pool tonight..we'll see what shows up in the morning. Yes i am running the filter 24/7 and brushing often. Before adding the bromide I had no real clue as to how long it would take or that it would gobble the chorine...but thanks to you I now know what to expect.

I noticed that my PH has climbed (maybe the heavy rains) but it is at about 8....I am kind of thinking that is from the clorox and the rain...should I just leave that alone while i am fighting this algae for now? Or should I throw some acid in the mix? My gut says to leave it for awhile...

Bromine is effective at a wider pH range then chlorine and if I am not mistaken the mustard products work better at a slightly higher pH. You might just want to bump it down to about 7.6 or 7.8 for now.

I may have killed off all the litle mustard algi!!!:eek:

I woke up to a clean pool and it held alot of the FC over night. I topped it back up this morning and came home just now to a clean pool (aside from the tent worms) and I still have about 10ppm FC ( where as yesterday afternoon I came home to about 2ppm from the same starting point in the morning) in the pool. I am going to still keep the levels at shck levels for a few more days just to be sure...but I may have turned the corner thanks to you. Plus t he PH seems to have dropped to 7.6 on its own today....

So Next up i am going to raise my CYA and get my TA to come down some...but first I needed to kill this algae.

Thanks for the help...and fingers are crossed.

GLAD TO HEAR IT! Seems like you have turned the corner and I agree with keeping the chlorine up for a few more days to be sure.
Don't try to adjust the TA until the chlorine is below 10 ppm (there can be interferances with the pH and ALK tests from high chlorine) and you can probably add some CYA in the next day or two. Just remember not to clean your filter for a week after adding it becuase it takes that long to dissolve!

crap.....a trace was spotted this morning....i brushed and vacuumed in the rain....this stuff is NOT fun...:mad:

FC was 11 when I checked before bed...I added 5qts just to be safe...and it held during the night...but with a residual amoutn of this algae on the bottom this morning...should I be adding more sodium bromide tonight? I would think if I had any bromide left in the pool then the FC would be be dropping alot over night?