Can anyone please tell me if this is algae or not?

[whipstall]

Hello there!

I have a 20,00 gallon indoor pool in the UK sanitised with bromine and run year round at 87-88 degrees. I recently returned from two weeks' vacation to find a brown organic growth around the light fittings and in the grouting between tiles (especially in corners). I initially thought it was the dreaded black algae, but (i) it's easy to remove with a nylon brush (no need for steel and hard scrubbing) (ii) it's brown, not black, and (iii) it doesn't seem to have the skeletal structure a lot of people describe.

The photograph shows the organic matter (whatever it is) having rolled over into a tube in my hand - it was floating in a thin, leaf-like fashion in the water after I have brushed it from the wall of the pool

I recently had a problem with white tissue mould which I was eventually able to eradicate with some chemicals designed to eliminate biofilm and wonder whether this is any way connected with that.

Any thoughts or suggestions on what this is and how I can permanently eradicate it would be much appreciated.

 

[Stuamurr]

Is this an indoor or outdoor pool? I don't think it is Algae, as it's pretty unmistakably slimy and I doubt it would roll up in your hand either, or float like leaves after brushing off, Algae usually 'poofs' into a fine dust in the water when brushing.

It sounds and looks more like some decomposed leaves/garden debris to me - presuming this is an outdoor pool.

Did you lose your effective bromine residual during your vacation?

Regards
Stuart

 

[whipstall]

Hi Stuart,

The pool is indoor and it's quite possible the bromine residual diminished whilst I was away. I normally run it at about 4ppm and have a brominator but wasn't able to monitor it whilst away. I have a maintenance guy who topped up the brominator during the vacation but since he didn't sample the water I have no data for whilst I was away.

Thanks for confirming my suspicions about algae - it doesn't look like the green algae I've encountered before.

Regards

Nick

 

[Stuamurr]

Indoor pool eh? I would likely be suspicious of dirt being tracked in from outside/poolside etc, Q. Do you operate a good poolside cleaning regime, including footwear tracking dirt in?

Not having worked with bromine for a looooooonnnggg time I'm really not sure about sanitiser residual loss and it's effect.

 

[whipstall]

We try to keep the pool surround clean, but inevitably there is some dirt transferred poolside from time to time.

In the absence of any advice to the contrary my plan is to replace the filter media (I have a Dacron sand filter but will am replacing the sand with recycled glass), having shocked the pool and running a high bromine residual for a week or so. I'm also using some of the anti-biofilm pucks I used to get rid of the white tissue mould problem I had earlier this year.