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Hey guys i was feeding my res and i saw this what are those brown things it is a problem or not (sorry for bat english )

The takn is full of those spots so what should i do

Could be algae. How often do you clean the tank? I usually just use a paper towel to wipe things down. If the problem is excessive, then I would take the turtle out, clean and do a water change.

Looks like diatoms. Very common if the tank is newly setup. Like steven mentioned just wipe them off, it will go away after a few months.

i clean my tank once in 3 weeks or 1 month they are all over the place on the stones,shells,mini castel ,glass EVERYWHARE the setup is not new

How long do you keep the lights on? You can try cutting back on the lighting period or shield the rest of the tank from the basking light.

i open the light in 7 am and close it in 11 pm

You could turn it off sooner. Most of us follow the sunrise/sunset times for our lights. Also try to keep the lights focused over the basking area.