The person at the pet store could actually be somewhat right. The flash from the camera for sure startled them, we always use no flash. As for the light, there have been people that claim albinos, and some random geckos, are much more sensitive to light. That being said, IMHO, a properly sized, daylight & UVB bulb is ideal. We have a 40W for a 20 gallon long enclosure. As long as the wattage isn't too much heat and the like, the day bulbs are just fine.
As for the substrate, I was attempting to be firm, please understand that the regulars here get a lot of messages from a lot of people who probably shouldn't be keeping geckos. I'm not including you in that category at this time, however, something as simple as laying down a layer of papertowels over the sand so that geckos can't get to the sand doesn't seem like something that takes a week to get around to, maybe 5 mins. I didn't feel like you were understanding that the sand was doing real harm and you were risking the life of your geckos by waiting, even just a day. You had been told last week (you even said you listened to your brother, I believe, and you admitted to being wrong at the time) that the sand had to go ASAP. If you still haven't taken care of it, then it is irresponsible.
I noticed in your recent message that the other has stopped eating. It most likely has eaten some sand and is impacted as well or caught something from the first. Now you have two very ill geckos. Lay down some papertowel, ideally instead of the sand, but at least over the sand to get it down right now. Fine a herp vet, if you can't afford a herp vet, try back at the petshop and make them take the geckos back. I am sorry, but there is nothing more we can tell you to help. Our first gecko was sold to us with parasites and we lost him with the best of care and a month of liquid feeding, it is a hard lesson to learn that good and healthy geckos are sometimes very hard to come by. Good luck, I'm hoping for them.
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0.1 Albino Leo Gecko
0.1 Crested Gecko
1.0 Dear Boyfriend
Departed: Harvey and Spock