Sticky oily deposit on indoor pond liner

"D. J" wrote in message
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"Reel Mckoi" wrote in message
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"D. J" wrote in message
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It sounds like a combination of LOW-LIGHT algae and a bacterial
coating. I had something similar in a fish tank some years ago. It was
solved by increasing the amount of light and more partial water
changes. You may also need a bigger filter. You may have too many
fish in your pond. What about plant filtration? Do you have plants?
You may be feeding them a little too much for the amount of *partial*
water changes you're doing.
--
McKoi.... the frugal ponder...
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Thanks for the comments, and Yes, I do have very low light for the pond,
I only turn on the 160 watts light when I want to see the fish, it's in
the basement, so I only run a 23 watt energy saving light when nobody is
in the basement.

** This is not enough light. Not only that, but your fish are living in
semi-darkness which doesn't seem healthy for them. Cichlids aren't cave
fish. Did you ever look in a toilet tank? You know that reddish slimy
stuff that lives in the darkness there....? This is the same stuff
growing on your liner, plus some bacteria for sure.

I have 30 cichlids range from 4" to 12", my filter is 2400GPH
wet/dry, my nitrite and ammonia is always 0 though, no plants, change
1/3 water every week, and feed them 3 times a day as much as they can
consume in 5 minutes.

** That sounds fine - you do need to get some good lighting in your
basement and leave it on at least 10 to 12 hours a day. How high is your
phosphate and *nitrate* levels? Not nitrite, but nitrate? I don't see
where anything is removing these two pollutants.

I will turn the primary light on for a few week and see if it improves.

** 160 watts is not much light. You may want to consider those natural
daylight fluorescent lights and hang them as close the water surface as
possible. I also had indoor chchlids (lake Malawi) in a 55 gallon indoor
tank with 160 watts of natural daylight fluorescent tubes a few inches
over the surface. Nice green algae grew that they nibbled on constantly.
I left the lights on 12 hours a day. The tank was also in a very bright
room that got sunlight from a nearby large window most of the afternoon.

Are you breeding them? What type are they?

--
McKoi.... the frugal ponder...
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Thanks for the great insight, today I thoroughly clean the pond again,
upon examining the sludge carefully, I found it feels very close to the
silicon paste that plumbers use to seal the water pipes, it is extremely
water repelling, so when you say LOW-LIGHT algae, do you actually mean
Diatom? I will try to add more light to the pond and see.

I don't breed them, they are all large Central American and South American
cichlid, mostly Parachromis and Amphilophus..

DJ
Forgot to mention my Nitrate level is 10-20 ppm usually, and I don't measure
Phosphate.