The eggs should be on dry perlite, above the water level. If you had light diffuser grating on top of the perlite: then it would suspend the eggs and you would have no chance of water contact. Resting the eggs on top of the perlite is fine, but, you have to make sure that the top level is completely dry. If water comes in direct contact with the egg then you will have problems.
I'm sure you have seen plenty of photos as examples.
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