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How big is your turtle? 1.4 inches
How long have you had it? 3 weeks

What is the water temperature? 28 - 30 degree Celsius
Did you use a thermometer? Yes
Are you using a water heater? No
How much water is in there? 1inches for quarantine. 6 inches for swimming and feeding
Are you using a water conditioner? Hypo to dilute chlorine
Are you using any filtration? No. Change every few days

What is the basking temperature? 32 degree Celsius
Is there a basking light? Yes
Is there a basking platform that is easy to climb on? Yes
What kind is it or what is it made out of? Plastic
Is there a UVB light? Yes but not in use everyday

What have you been trying to feed it? Turtle floating stick
When was the last time your turtle ate? Today

How big is the tank/pond/enclosure? Plastic aquarium not very sure bout size
Is the tank near a window? No
Is the tank in a room with a lot of activity? No

Have you read the Basic Care section? Yes
Have you searched the forums for similar situations? Yes but unsure its the same case as the picture provided is seems different

Is there any other unusual activity/symptoms? No

I found its colour is kinda light compare with another one that i bought them back together.
Today i found out that there is this white stuff on its shell gets serious as it was there for almost a week or two.
He/she has been in the water for most of the time and this means that its hard to see him/her basking.
this fella is eating and swim well all day long.

Hard to say, though it doesn't appear to be fungus. Can you do a soft, gently scrub (use a new toothbrush) and see if it stays the same?

Okay!! I tried brushing them and its gone but there is white/lighter colour on its marginal like water stain or something that I'm not too sure...
It was there for sometime since i brought it home till now...
Just fyi he/she doesn't bask much so it cause it this way?

Not basking enough can cause a variety of problems. Do you know if you have hard water?

Should I bring him out of the water and quarantine for only basking?
I'm not very sure bout if i have hard water but i have the other 5 RES include the 1 I brought back together with this one doesn't give me any problems before.

I'm not too sure what's going on, so I can't advise taking him out of his tank. How often does he bask? He's kept with the others?

I just got him back so he is in the quarantine with another 1 that I bought it home together.
Now he has such problem so I have moved him into individual tank.
What I can say is that he don't bask cause I've never seen him really basking before.
What I've seen is that he will goes to the platform for a few minutes then he move back to the water.

Last night I tried bask him the whole night.
Today I can see that his colour is darker but there is still white film or water stain likes look on his marginal.
Another thing I found out is that on the line between each shell/scute on its carapace turns a little dark colour (dark green/black).

Can you post an updated picture of the shell and his setup?