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Originally Posted by Pandagobyguy
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I think any of these would be OK, they each have their subtle differences. What you want to do is match the screen size to the lamp size as best you can. A small lamp might output the wattage/intensity you need, but might be too focused and result in a hotspot.
Quote:
Originally Posted by SantaMonica
Sounds like detachment. Common for waterfalls, in bigger screen sizes, if the lights can't burn through to the middle of the screen in order to let water in there. The bigger size has no way for water to get to the middle when it's full.
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No, it's not likely to be detachment, I think you're jumping the gun without having all the information.
This is why I asked about the pump failure.
I've had a pump fail for a day or so, sometimes when you have a power glitch a pump won't restart correctly and the impeller will get stuck in a vibration cycle, especially when the water column it is pushing up starts to fall back through the pump while the pump kicks back on. I've had this occur. Sometimes the pump will "catch" and the flow will kick back in, leaving you with a mystery about what happened. So if the flow is lost for a day or two while the lights are running, the screen cooks, and the leftover dried out residue does not allow for algae to easily attach for some reason. IME when this "baking" of the screen happens, you have to soak the screen in vinegar and scrub it down to the canvas and start over with the maturing cycle.
The other way this can happen is a bit of a mystery effect that I refer to as "whiting". This is when you don't have a pump failure, but the algae will just turn stark white very quickly, like overnight (less than 24 hours). I've seen this happen repeatedly with one particular tank and I was not able to come up with an explanation - growth would start out OK, it wasn't over-lit (intensity and duration were not extreme) but a few days in (with just "whispy" green growth, and usually after a harvest, so not thick and light-blocking) the growth would just turn white.
My only fallback was that there might be a particular nutrient level that drops and causes a full inhibition of production, such that the incoming light cannot be adsorbed and the result was a cascading failure of algae cells. Just a theory that fits the facts, but this is so infrequent of an occurrence that I haven't ever been able to nail it down.
@sensei let me know which of the 2 scenarios seems to make sense. Also did anything else happen in this time period? Storms? General power loss? Have nutrients dropped in the system significantly over time?
The last question there - if everything was hunky-dory for a long time and then this suddenly happened, that could also explain it. You may have hit a point where the intensity/duration of the scrubber lights were left alone while the "balance point" of the overall system dropped below that and you had the "whiting" cascade.