Managanese bacteria slime vs black algae in hot tub

dankasprick83

Member
Aug 24, 2022
12
Lake Orion, MI
Hey guys,

We have a 395 gallon master spa lsx850 purchased 4 years ago. We use liquid chlorine to hold around 4-5 ppm with SLAM once per week and TA around 50. Six months ago we started getting a black slime building up around our jets (pics attached). I've drained the hot tub and treated the areas in question directly with bleach multiple times and it dies back within minutes. I've done a purge with ahhhsome each time and brushed everything and replaced filters. After a thorough clean out the slime is usually gone for a few weeks but then starts to pop up within about a month until every jet is completely encircled.

We have a subdivision wide group chat and almost everybody has had large amounts of what looks like the same substance accumulating at the aerator on all of our faucets. Our township says everything is fine with the water but they don't test for manganese. I've had many people suggest to me that this is black mold, black algae, or mildew but I've consulted a few resources that suggest this is a slime made up of manganese eating bacteria (though nobody has had it tested).

Has anybody else encountered this? Are there any pre filters that can be used to successfully filter manganese from our city water supply?

Does anybody have any info on what the highest ppm FC level is for an extreme shock before spa components or fiberglass shell start to deteriorate?

Is there anywhere that I can send a sample of this in to have it tested?

Any help is much appreciated!!
 

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I dunno about the manganese slime theory …

I’m not saying it doesn’t exist or that it isn’t a problem in some circumstances. But you are running a hot tub with a significant amount of chlorine sanitizer and it has been purged and cleaned fairly thoroughly. In order to produce the slime, bacteria would have to be present & growing but that particular bacteria species is very susceptible to disinfection by chlorine.

So is this tub kept at a proper FC level or is it allowed to go down to zero? That’s the only way bacteria could colonize and grow.

A simpler explanation is that something inside the tub is breaking down like a rubber seal or a glue joint or some bit of flexible tubing. Only a very thorough examination of the tub’s interior components could determine if that’s the case. And that is best handled by a hot tub repair specialist.

Maybe @RDspaguy has seen something like this before??
 
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I've consulted a few resources that suggest this is a slime made up of manganese eating bacteria (though nobody has had it tested).
Can you identify these sources?

Did they provide any evidence or logic behind their diagnosis or is it simply speculation with little to no basis?

Maybe find a local testing lab.

There are usually resources that can test well water and other water for a variety of contaminants.

Contact the water supplier and ask for a full water quality report and ask them for any assistance they can provide.
 
Yes, I've seen this before. No, I don't know what it is (besides gross). I have no opinion on the water supply question except have it tested.
Jet gaskets can and do get water behind the leading edge, and farther as they deteriorate, which provides a fantastic place for stuff to hide from purges and sanitizers alike. A pack of cheap toothbrushes and some liquid chlorine, algeacide, or acid, or even some purge perhaps, and alot of elbow grease should get it cleared up for a while. I'd remove the jet internals and pillows and clean behind them too. Ahhsome is great, but it only works on stuff it can get to. A purge with ahhsome after cleaning, with the jet internals and pillows floating loose in the tub, would not hurt one bit.
 
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