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Hey guys,

Have you ever seen this? This was in an indoor 24000 gal hotel pool on bromine. No windows. The pic is a yellowish slime/popcorn type of growth that looks like wet cornmeal. The pic was taken with my cell phone, so is not the best quality. Might help if you zoom in. The growth was located inside the far end of each of the 8, 12” long laterals of a single TR-140, 7 cu ft filter. The filter sand was oily and clumpy, meaning that I had to actually scrape the sand to remove. (It wasn't calcified or rocklike, but was tightly goo-packed to the point that the sides of the sand would stand on its own, from the top of the bed, all the way down to and through the gravel to the laterals, and everything had a slippery feel to it. It smelled like swamp water).

This was one of the nastiest filters I had to deal with in my 20 years of doing sand changes, which surprised me as the pool is typically low use, and this sand was only 6 years old. Pool water was very cloudy and greenish, which is why they called me in to do a sand change in the first place. They said they use a clarifier occasionally, “Crystal Blue”, which is your typical petroleum based type clarifier. They also started using a backwash product before backwashing a few months prior. Also said that the last couple of weeks, their bromine use has gone up considerably... ya think?

They typically keep bromine levels low, 3-4 PPM, but I have my doubts as the record sheets for both pool and spa showed the exact same readings almost every day. Not easy to do on bromine tablet feeders, as there is usually a wide variance. The controllers were old analog, ORP only, Chemtrol 205’s, and they were reading in the low 500’s, even after the pool shock was added. Could just be bad sensors. All in all, their are a lot of red flags that indicate maintenance is not very good, even though the maintenance person is CPO trained. This may be an issue with the owner trying to cut costs, and inhibiting what maintenance is done.

Anyway, I did the sand/gravel change, and replaced the funky laterals with new ones. Had them shock the pool with 4# of Cal Hypo, 46%. (They didn’t have any chlorine on site, and could only get 1# bags from local hardware store. It’s a very small town out in the boonies). Also put in 2 qt of Sea Klear to help clear the pool.
The next morning, they said that the pool was a little clearer. No reading on bromine. However, for some reason, the maintenance person decided to look inside the filter, which was a good thing. From what he could see, there were clumps of this cornmeal growth along the top inside of the filter.

I didn’t see it when I did the sand change, nor did I notice it in the removed sand. I’m assuming it came from the pipes, but at this point can't say for sure. Obviously the pool must have had a high chlorine demand for some time, and I’m guessing the growth must have been elsewhere in the pipes and let loose?

My only thought is that it might be some sort of biofilm growth, but but can'y really find anyone who has ever seen this before, much less finding it inside a lateral.  I told them to backwash again to remove the loose growth on top of the now clean filter, and to keep shocking with chlorine until they could maintain a bromine reading. I also suggested that they add more Sea Klear to help clear the pool. I strongly suggested that they really needed to consider to get off bromine and to upgrade to chlorine, as well as to upgrade their old controllers. This pool is around 150 miles from me, so can't really monitor it.

Even so, if it is biofilm, then have my doubts if the remedial treatment of just shocking to eliminate the chlorine demand will have much of an effect on any established biofilm. I networked a bit, and emailed this to Richard, Kim, Howard, Wayne, Clemente, and a few others. Most have never seen anything like this. Some think it is a cause and effect of using bromine long-term. Bromine has a history of being a fairly weak sanitizer, and does little for oxidation.

Lateral Growth-1.jpg