Very nice!

I believe that's a 300 gallon stock tank, not 400 gallon as rubbermaid does not make them in that size.

Exactly, get an aerator.

It happens on my tank as well. Get an aerator. It'll clear it right up.

Anubius would be a terrible choice as a feeder. I grow it in my planted tank and it's probably doubled in size in 2 years. Fast growing plants are going to be things like Anacharis, Water Lettuce and Water Hyacinth. Also, these need fairly high light. The simplest way to grow them is outside. Fill u...

I've never heard of this sort of thing. It all seems very strange, as turtles in the wild sit in the sun for hours at a time. Mine sit outside the pond in 100 degree weather. I think there is something else afoot here.

Where in Southern California are you? There's a great pond plant store in Sunland. Also, people on craiglist are giving away pond plants for super cheap this time of year.

It's not, it's in the ground.

Between 150 and 200 I believe.

Turtles are such divas when it comes to laying eggs.

My big 15 year old has a whole pond to her self. She has a 4ft. basking area/nesting box (2ft. of sand) and still chooses to lay her eggs in the water every year.

Floating plants like duckweed, hyacinth and water lettuce would be your best choice.

Looks like Shell Rot. And a very serious case at that.

Can we get more pictures of him? He looks like an old melanistic male.

Fill a tub or container with about 4" of sand or a sand/dirt mix. Let her in there for an hour and see if that helps her.

How is is your tank?

I don't think there are any basking dock that will really be comfortable to a turtle that size. Cork bark may be good.