I have a few Turtle questions?

That tank would in know way 100% not work, that tank is not even big enough for one turtle.

They need 10 gallons per shell inch so say you have two turtles that are 1 inch you need at least a 20 gallon tank, however I will warn you buying the minimum size tank will not save you money because sliders out grow them in no time.

You are right, if they are not warm enough they will not eat make sure you keep your tank around 70-75 degrees with a basking area with uvb uva at around 85-90 degrees and an area where the turtle can get totally out of the water and get dry.

I started out with a 30 gallon tank with three res hatchlings

It lasted around 6 months

then I upgraded to a 150 gallon indoor pond

I am now looking into getting a 300 rubbermaid stock pond

If you have a female slider she can get up to 10-12 inches full grown

A male around 6-8 inches

There are numerous reasons why a RES may not eat. A recently hatched RES may not eat for several days while they are sustained through their yoke sac. Cold temperatures may discourage RES from eating as their metabolism slows down. Water should be a constant 75-78 degrees F. Illness and infection may suppress appetites and if other symptoms are present, they should be thoroughly investigated. RES can occasionally become tired of the foods they are receiving and may be just looking for a change. A mature female RES may refuse to eat if she is preparing to lay eggs. Finally, stress may discourage a RES from eating; this may especially be true if this is a newly acquired turtle.

Lighting and temperatures should be carefully checked. Try offering treats and live foods to entice eating. Smelly foods or ones that are brightly colored may appear more appetizing. Boiled chicken or pellets soaked in canned tuna water may be useful. If you are feeding your RES in a separate container, they may feel more comfortable in their regular tank. If you are feeding by hand, they may be reluctant to take it. Most hatchling and new RES need time and space to adjust. Once your RES begins to eat, you should attempt to slowly switch it to a more appropriate diet.

Usually they ned to star out with a 50 gallon i have mine in a 30 gallon though cause it only 4 inches every ince is x10 so inch would be 10 gallons i use to have a 10 gallon for my baby RES and the tank was only 11.oo at mejier or summ

The move might have thrown them off their feed.Temperature might be a factor. Aim for 80°F water and a 90°F basking area. And don't be absurd about tank size. Sliders are worse than other turtles about needing elbow room. Even a 50-gallon tank might be crowding them. If money is tight, consider a stiff plastic wading pool.

I hope you're kidding about a 5gallon tank for two turtles. You'll need at least a 60gallon for both of 'em. And once they get even bigger you'll have to get about 120gallon tank.

You need to have two filters, a UVB light, a big enough baking area for both of them, proper water temperature, a heater (the ones specifically for turtles), a good diet for them, etc, etc.

If you can't take care of them properly then you should re home them to someone who can.

5 gallon is WAY TOO small. the min. they need is a 50 gallon when full grown preferably like a 65. so as they are babbies now a 20 gallon long is perfect.