QUOTE(mommy5 @ May 19 2008, 02:00 PM)

My questions are:
1. whats the best way to re-do the under gravel filter (ie: what do i do with the fish when i put the filter under the gravel)
2. how often does a tank need to be cleaned
3. why is the food on the bottom rotting
4. is this tank big enough for 4 of these tetra glo lite
5. does there need to be a heater in the tank
6. how often does fresh water need to be added, and can i use tap water
1. Stick the fish in a container with their current water, remove the gravel from the tank (or even move it aside slightly) and put the undergravel filter under the gravel (the base that is, not the top).
2. Every few days with the current fishload, you are very overstocked.
3. The food isn't being removed by the filter, or you are overfeeding. Since the filter was positioned wrong, I'd go with "the food isn't being moved by the filter".
4. No, you are very overstocked. The rule for tropical fish stocking is "one inch of tropical fish per gallon of water". ((Note, this is for tropicals only and shouldn't be applied to goldfish or koi.))
5. 1 gallons can not be heated safely by heaters, so for the safety of the fish, no.
6. Water should be added when you change the tank. Remove your fish from the tank before adding water. Put them in their old water in a container while you change the tank ((Since you have a 1 gallon you need to do 100% waterchanges). Do not //ever// (I use strong emphasis on this) put tap water into an aquarium without first using water conditioner to remove the chlorine and hard metals. It will kill your fish.
I suggest you take the fish back, or buy a five or ten gallon tank. As I mentioned above, you are really overstocked which can lead to disease and death in the fish. They need a lot more room then just a gallon. A five or ten gallon tank would give them plenty of room, and then you could safely add a heater (which tropicals need), decorations, and possibly more tankmates to.
After reading around it seems like glo-lites, since they need large schooling numbers, are best housed in a 20 gallon. Maybe you could consider upgrading after moving them to a five or ten gallon.
Also, please browse around this website (or maybe a tropical fish forum) to learn about the basic care of fish and their tanks. Having fish can be a joyful and fun experience if they are cared for properly.
http://www.fishlore.com/profiles_glowlight_tetra.htm^ There is a link that has really good information on the type of fish you have, their requirements and such-like.
For now, maybe you could move the tetras into a five or ten gallon rubbermaid, buy a heater and filter and give them a temporary setup. I strongly urge you get them out of the one gallon though.

I hope this helps out a bit, and good luck.