Hi! Welcome to the forum
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You've gotten some great advice by Lisa!
Cover 3/4 of the top screen with either Saran Wrap or foil. This will help to keep in humidity. Adding live plants also helps to hold moisture in. Their humidity should be in the mid to upper 70's.
You may have to mist the tank more often or get a fogger. You'll definitely need a hygrometer to monitor the levels. You can mist the tank with distilled water if you don't want mineral spots on your glass. You can also non-chlorinated spring water or dechlorinated tap water. Never use straight tap water or bottled drinking water. Chlorine is toxic to frogs.
As noted, never use water with chlorine in it. Use only spring water or dechlorinated water for the water bowl and for moistening the substrate. Do not use distilled water for these either. Distilled water lacks trace minerals and actually pulls electrolytes out of the frogs if they soak in it.
A pothos plant (Epipremnum aureum) is a great starter plant. It grows nice and tall and tree frogs love to climb in them and perch on the beaches and leaves. They often sleep on the leaves. It is not necessary, but they would love it and it would help to keep the moisture up.
You could also add more fake plants. They will help hold more moisture in too by holding several droplets. Be sure all plants have smooth edges. Rinse in dechlorinated or spring water to remove dust and any possible mites before adding them to their home.
All live plants must be rinsed of all fertilizers and dirt. Rinse them until there is nothing left on the but the leaves, stems, and roots. Replant them in coconut fiber bedding or plain, unfertilized plantation soil. Fertilizer is also toxic to frogs. You may want to plant them in a pot with a smooth rounded plant climbing post. A dried curved bamboo post works great for this. You can gently wind the stems right up around it. Rinse again in dechlorinated water and only water the plant with dechlorinated tap water or spring water.
Adding a tall plant will make them feel more at home. They may be climbing high in the glass as they would on a plant. It is okay that they are on the glass, but if you had a tall plant for them, they'd more likely be in the plant. Tree frogs like to climb high
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You can also provide branches or vines to climb on. Anything brought in from outdoors must be thoroughly rinsed. Baking branches at 350'F in the oven for 30 minutes will kill off most insects that may be lurking in the branches.
There is also a bleaching method, but you'll need the dechlorinator solution to use this method.
Many pet stores that sell amphibians and reptiles will have artificial vines you can use too.
As Lisa has mentioned, covering the back and 2 sides of the tank with a background will help them to feel more safe. You would only have to do the sides. You can use anything from brown paper bag, to craft or construction paper, fabric, aquarium background designs, etc. they would most prefer something that looks like trees and leaves, but anything will help.
For heat, you can add the UTH heat pad or a use a heat lamp with a dimmer and a red heat bulb or ceramic black heat emitter. Start at the lowest setting and slowly turn up until you reach the desired temp. You will need a thermometer gauze to monitor the temp in the tank. Heat lamps and heat emitters will cause some drying in the tank. The heat pad may be better.
I use different heat sources for different tanks, depending on the type of frog in the tank and that frog's needs. My dart frog tank is a 12x12x18" quarantine tank that I use a small heat pad on the side. It keeps the temps in the 70's with my home furnace set at 73'F. The heat pads come in different sizes. A medium heat pad work work nicely for that size tank. I have found varying ranges of proper temp for them from 70-85'F. I would keep the range in the middle around 75-80'F daytime and a few degrees less at night.
Your babies are tiny yet. If the crickets are not as small as or smaller than the distance between their eyes, I would get some flightless fruit flies. Feed daily and remove any uneaten insects they do not eat. Bowl feeding works well for this. You can use a smooth edged glass bowl to keep their crickets in. Fruit flies are harder to keep in the tank. You can slide the screen lid into a nylon and replace the lid. Be sure to lift and lighting or heat lamps up off of any nylon or Saran Wrap on top of the tank. At there size I would definitely recommend some fruit flies until they grow a little.
Supplements: Calcium with vitamin D3 is needed. Without it, your frogs can develop metabolic bone disease and will develop illness, tetany and death. It is a powdered supplement. Lightly dust the bugs every other day with the calcium. Using a punch in a baggie or cup works well. Use the multivitamin powder one day a week as a dusting, but not on the same day as the calcium. Be sure the calcium has vitamin D3 in it for proper absorption.
Congrats on your new babies! They are adorable!
. If you keep them nice and warm, moist, feeling secure, and give them some more nice things to climb and hide in they should be happy and should start eating for you
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Oh! You may want to try using plain paper towels as substrate for a few weeks until you know if they're eating and pooping. It's easier to watch for feces. Change the paper towels daily.
Read around for some posts and you'll learn lots!
Again, welcome
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