I have three 5" fish in my 38G tank and I did a 100% w/c on last Saturday. The Nitrate reading was at 10PPM yesterday (Wednesday). What nitrate level do you people normally keep in your tanks? I know it needs to be kept as low as possible but I dont want to waste water as well.

Would fish grow fatter and quicker in a Nitrate 0 water?

the less nitrate the better it is advised not to let it get above 40ppm for healthy fish ...as for 0 nitrates you can acheive that with green water (green algae) which I can only make the yucky brown stuff....just feed less it may help keep it lower..having low nitrates is just healtheir for your fish all around

I'm just like you. No matter what I do, all I get is brown algaes because I dont get direct sunlight in my room. I guess the only way to get green algae is to get direct sunlight onto the tank.

Ammonia + Sunlight = Green Algae

correct?

It is my understanding that if your nitrate climbs above 20 ppm between water changes that that is an indication that you are overfeeding. I know that you are intentionally feeding heavily to promote growth of your fish. I don't think that low levels of nitrate are apt to inhibit the growth of your fish -- you should probably be doing water changes with the aim of maintaining nitrate of 20 or below and removing the growth inhibiting hormone that goldfish secrete. There is an interesting post somewhere in which Daryl (I think) describes how a continuous water exchange system maximizes the growth of fish by constantly removing the growth inhibiting hormone.

Someone around here (can't remember who) told me that brown algae is a stage that relatively new aquariums go through and that once you get through that stage (within 6-12 months) that brown algae will not recur and that green algae will predominate. I have a relatively new aquarium that gets strong natural light 6-8 hours a day and it still has brown algae.

I think that the equation would be nitrate + sunlight (or full-spectrum lamps) = beneficial algae.

Oh, I didn't know that before. Thanks for the information. I guess I need to leave the light on for at least 8 hrs a day. Originally I thought the brown algaes were caused by weak light (not intense enough). Now I hope I will get some greens ones soon.