I was doing water change today, and I saw these markings on the glass. Are these markings from the mouth suction of my bushy nose plec? See pics at link below...

Plecostomus Tracks pictures by aquariumninja - Photobucket

could be but i'm not sure to be honest I have two plecos and never noticed markes on the glass from them

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"Being ignorant is not so much a Shame, as being unwilling to learn".-- Benjamin Franklin

I like the quote in your signature, Summer. Very nice.

It can be, but that also means the inside glass is pretty dirty. Next time when you do a water change wipe the inside glass.

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SUCCESS IS MEASURED BY YEARS, NOT MONTHS!!!
220 Tank build
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Inside glass isn't very dirty at all. I just zoomed in on the markings because they were very faint and were only visible at a certain angle under Verrrrry high light from the LED strips placed behind them for a better photo exposure. The zoom and narrow focus make it impossible to see the clean aquarium behind the glass. I'd never seen anything like this before because I keep the tank and water so clean... Obsessively so. I do water changes about tree time week 40%. I pre-treat and "age" water in barrels to the same temp and pH as the tank so the water changes are completely stress free. I keep up this regimen in preparation for the discus fish that will eventually be present. Very low nitrate ever. Also UV sterilization keeps algae at almost zero, so I certainly feed veggies and algae wafers.

They look like OCWD marks
Obsessive Compulsive Water Disorder

I'm not sure what they are but if something is leaving marks then there must be some kind of build up on glass to get that hazy appearance.

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90 gallon, 1 Iridescent shark, 2 Pleco, 3 Goldfish, 5 Cory cats, 2 Nerite snails
5 gallon hex, Blue Crowntail Betta, 1 nerite snail,