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Green Water Line Slime and Foam


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Thanks to this forum I have been able to well maintain our in ground spa that was installed Oct 2020. Unfortunately my husband became ill and landed in the hospital for a week and the spa wasn't tested or used for 9 days.  We use bromine and hayward brominator/chlorinator that I think was designed for pool use.  We usually keep it barely turned on to maintain bromine levels, but with lowered usage over the holidays, even that was too much.  So I had been titrating by turning it on and off as needed.  Bad idea, as it was off during my inattention.  When I opened the spa it smelled bad, was foamy and had a thick green sludge along the water line, that I assume is algae. So far I have tested the water, jacked up the bromine, wiped the slime using a sponge and bucket of clear water, and added a dose of Spa Guard Natural Enzyme.  I also have been skimming off the foam, turning on the jets to create more so I can skim off more. If this was an above ground spa, I would be draining and refilling, but its a 550 gallon in ground spa and outside temps are 25 degrees and going down to 9 degrees tonight. We circulate the water 24/7 to keep it from freezing. We might get temps above freezing on Monday, but I don't want to not have circulating water in the pump and heater any time until then. Any suggestions on how to get it safe for use again?  I've seen people mention SLAM, but that is with chlorine.   Can I do that with Bromine? Do I need to order and use an algaecide? I imagine I also need to brush and vacuum, which will require thawing the breaker box. We had an ice storm, followed by snow.  Just getting the cover off the spa was a beast. Condensation under the plastic covering of one of the foamboards filled it with so much with water that it was bowing and I had to bring in a couple of helpers to move it. 

550 gallon in ground acrylic spa with above ground pump, cartridge filter and heater.

Bromine tabs sanitizer in Hayward brominator/sanitizer.  

Taylor Test Kit. Ph typically maintained well with just twice weekly additions of baking soda. Occasional use of MPS and Enzyme. Water changed when TDS start going up above 900 or so.

Current PH 7.8, TA 50, CH 200, TDS 596, LSI .11  (Using Taylor sureTREAT App)

Water cloudy and foamy.  Waterline scum was dark, army green. 

Thank you in advance!






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So, its looking much better.  No more foaming.  Bromine levels are definitely higher than the 10ppm, top reading on my Taylor test kit. No signs of algae anywhere.  I missed some in the skimmer basket area, and wiped that all out better.  Brushed and skimmed with aeration.  And skimmed and skimmed and skimmed.  Water no longer has any green tint, but is still cloudy looking.  Turned the bromine off over night and levels were still high the next day.  Have the brominator set to 0 now, which is just above Off, waiting for the levels to come back down for safe usage.  I imagine the cloudiness will eventually filter out or be resolved with our next water change, which we expect to do in March. At this point I plan on never turning off that brominator completely.  Also, thinking if we had turned down the water to 50 degrees, the algae wouldn't have taken hold. 

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Sorry I missed your first post.

Slam is a term and process advised on another pool forum, and is meant for pools. I would just drain and refill a spa before going through a slam.

In a bromine system adding chlorine (or any oxidizer) will generate bromine from the bromide in the water. Which is fine in this case, but will result in stupidly high bromine levels, since you want to add 30ppm chlorine for algae control.

Depending on the filter, it may not get the tiny particles that result from oxidizing algae out of the water. What type is it, sand, cartridge, or de?

I suggest you shock with liquid chlorine (3 cups) or plain unscented bleach (8 cups) then use ahhsome spa purge as directed. Drain and refill.

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