Tiny bugs, algae and GSP

Question
QUESTION: I asked Nick these questions and he replied that he couldn't help. Hopefully you can.

I have a small Nano tank with a green spotted puffer fish and a fake rock. He is a messy eater but I don't want to feed him too little. Recently we had a scare when he scratched his belly (he tried to jump ship and found himself in the filtration system). We set him up in a hospital tank for a couple weeks and took the opportunity to rinse his sand and clean the tank well since we were having problems with a gross thick, slimy red/brown algae. Now he is back in his nano tank and doing well. The gross algae has not returned but now there are little white bugs and a fuzzy looking brown (light brownish grey) algae. He seems to like the tiny little bugs and snaps at them as they float around.And new today there are little reddish pupae looking things.  I  don't know how they got there. The rock is a fake or dead one. And the sand is the same as before, just rinsed. From what I have read it seems the tiny little bugs are ok, but I don't know if the brown algae is good algae. Or what the new pupae are. And is this a sign that his tank is healthier this time around?  Or worse. And am I overfeeding and causing the algae? How do I know when he full? I don't want to over feed him but it seems he'll keep eating till he pops.
Thanks for whatever help you can give. Sorry its a long one.

ANSWER: Hi Heather. You are right about the little "bugs" they are copepods and signs of a healthy tank. They are also an excellent food source for your fish. As far as where they came from, they could have came from the substrate if you used a live sand, the water that the puffer was packed in when you bought him, and sometimes even the food depending on what type you use. I can not tell you if you are over feeding because you didn't tell me how often or what you are feeding your puffer but feeding once a day as much as the fish can consume in two minutes is the general rule. Puffer fish as well as other predatory fish can over eat causing fatty liver disease, a bowel blockage and obesity leading to shortened life span.
Most algae are not harmful to a fish tank but just a sign of a water quality issue. There are several explanations for the algae; it could be a brown hair algae, a form of cyanobacteria, or green hair algae that has become covered in diatoms. All of these are a sign of a water quality problem if they are growing out of control. High dissolved organic wastes, ammonia, nitrite, nitrate, iron, and phosphate in your water will aggravate an algae bloom and make it difficult to control. You may want to test your water for these things and do more frequent partial water changes, using only reverse osmosis or distilled water rather than tap or spring, then you are. I am a little concerned about the fact that you have a green spotted puffer in a tank that you are calling a nano tank. These fish require at least a thirty gallon tank and can get to be 6-8 inches full grown. They are very messy eaters and can pollute a small tank rather quickly. This may be the reason you are seeing all kinds of funky algae cropping up in your tank.
The identification of the small reddish pupae looking thing is hard because i am not sure what type of water you are keeping your puffer in. Is it brackish or full strength saltwater? This is going to make a very large difference in identification due to the varying creatures that live in fresh, brackish or salt. Also when you say pupae looking I am not exactly sure what that means. Do they move around? Are they mobile and worm like? Any legs? Are they on the glass, rock, sand or all of the above? Flat and round? Long and skinny? the list goes on.... If you want to get back to me with a better description I would be glad to assist you on this further and I hope that I answered the rest of your concerns for you.

---------- FOLLOW-UP ----------

QUESTION: I was told at the fish store that my little puffer was a good fit for the nano tank. Its 6 gallon and he is in full saltwater. Since purchasing him (6 months ago) I have seen a very large GSP and was not aware they got so large. Mine is about an inch and half long.
 The pupae things are changing color and stationary in the sand. I thought one might have moved but I think it was the water flow. I guess I am not as concerned about what ever they are as the algae and tiny white bugs. But since the tiny white bugs showed up after not being there for 6 months I was unsure of where they could have come from. He does seem to munch on them and there are not as many as there were when I first wrote.
I feed Apple once a day and its a frozen mix of protein and veggies (thats my non-fish name for it) and I feed him till his little belly is round. He is very messy and I don't know what I can do help with cleaning. I've read several different answers. We did try buying some larger snails in hopes that since they were so big he would leave them alone. But then we had to hospitalize him and put the snails in my boyfriends tank while we cleaned the nano tank Apple lives in. We have not returned them.
Anyway. Thanks for your help. If you have anymore advise, I'd love to hear it.

Answer
HI again Heather. First of all you have to get "Apple" out of that tank! It is way too small for him and this is why you are having trouble keeping the tank clean. Fish do not grow to fit the size of their tank. If kept in too small of a tank it will stunt their growth and eventually cause death! This fish at this size should not be kept in a tank smaller than a 20 gallon if he is kept alone. If this upgrade is not done you will loose him and soon! If I were you I wouldn't take any more advice from that pet store either. This is ridiculous that they sold you such a small tank for a fish that will grow to be 6-8 inches long! Puffers are fast growing too! Chances are that if he hasn't at least doubled in size in the last six months from when you got him then the chances of him having his growth stunted has already started to happen. Get this fish into a larger tank ASAP!