I just have a hanging on the back thing. Premium aquatics is close to my place and they have dry rock for 1.50 a pound I'm going to pick up some more this weekend. Based off my pictures how many more pounds do I need? I really just want to find an affordable option for lights. I know u guys have mentioned a lot. :-( 250 is still more than I can do but maybe ill find a used light somewhere. And I'm just surprised that the nem is doing back cause it send fine I feed it twice a day and its never seems unhealthy.
A general rule of thumb is about 1-2lbs of live rock per gallon of water. So for a 20 gallon aquarium you would want at least 20lbs of rock in there. I have about a pound and a half in my 29 gallon and it seems to do the trick.
As for the hang on back filter they can cause some serious nitrate problems if not properly cleaned very often. They are fine for freshwater but because of the high demand for excellent water quality that a reef system has they can prevent you from being able to keep corals and that nem that you have. I do run an aquaclear 50 on my tank but I have modified it a bit. I use it mainly for water polishing. I run carbon and phosphate/nitrate reducer in it. I have a small sponge I use that gets cleaned every other day and is totally changed out every water change. That way you can prevent nitrate build up. There are some of us that use them this way. However, most people in the hobby get by with a good skimmer and plenty of live rock and water changes. If you don't run a sump, you could use a skimmer such as the Aquaticlife 115 Mini Internal Skimmer. I run one of these in my 29 and am very pleased with it.
If you want to stay on the cheaper side for lights you would do well to get a good t5 fixture. For a person just starting off I would look at
aquatraders for a good 4 bulb fixture. These are cheaper but would suffice for a beginner. It would also allow you to keep some soft corals.
With the nem, I think everyone else has you totally covered. It should not be that white and without proper lighting which you don't have at the moment it will surely die. It can then wipe out your entire tank. They need the most pristine water qualities and stability.
Stick with it, like most, we learn from making mistakes. Everyone on this forum has helped me out many times and you are definitely in great company here. I look forward to seeing the tank progress. :D