Water Change Frequency

[dmweise]

I have a 45 gallon tank with quite a few corals and fish. I have anemone as well. My tank parameters are generally idea zero ammonia, 0 nitrites, ~40 nitrates.

I currently do a 15 gallon water change each week and am starting to wonder if I'm doing this too often.

[Troutmasters02]

I do 5 gallons a week on my 65 gallon tank, not to say thats right or wrong, just thats what I do. Your nitrates seem high, water changes should help that a bit I would think. How long you been doing these water changes?

[tony]

short of doing a high percentage i really dont think you can do water changes too much

that is pretty high for nitrates especially with that many water changes are you skimming? are you using RO water?

[marshall.read]

first thing is do you know how much water you've displaced with substrate and live rock. if you're rock is very dense and you have lots of it then you may only have 30 gallons or less of actual water in the tank. if thats the case then 15 gallons ( or 50% of a total of 30 gallons) would be a little high. even if you have 45 gallons of water in the system this is still over 30% water change, which is quite a bit. its troubling that you're still reading nitrates despite these large and frequent water changes. i would recommend checking your water source for nitrates. its possible that your local tap water has some nitrates, or if you're using ro/di then perhaps your filters need replaced??? if your water source has no nitrates then you need to implement/improve some method of reducing your nitrates. a refugium with lots of macro algae is a popular method of eliminating nitrates, but others exist as well. while 40ppm of nitrates will likely not prove immediately deadly to most corals (although most anemones are much more sensitive to this than coral), i assure you if your fix your nitrate problem your corals will open/color up much nicer and their rate of growth will improve.

[dmweise]

I think my live rock and live sand displaces about 15 gallons. I do have a skimmer that is running. It has a lot of sludge that builds up in it each week. My nitrates are most likely high because of my high tank population. I'm considering removing six of my ornamental fish, five chromis and a devil damsel.

My corals do grow rather quickly. My mushrooms go on division binges at least once a month. My frogspawn has quadrupled in mass in the past year (I need to frag it). The star polyps that I have grow rather quickly and the zoanthids that I added seem to be doing well. My bubble tip anemone doesn't get too bubbly and generally looks like a long tentacle anemone. My long tentacle anemone has actually improved since I purchased it. It was almost bleached when I bought it and quickly browned.

I use RO to top off my tank. I put a reef buffer in it. I buy my salt water from the LFS. I never put tap water in my tank. Occasionally, if I'm out of RO I run to the convenient store to get distilled water (not copper filtered).

[wesheltonj]

Try a different test kit.

[marshall.read]

glad to hear your fish and coral are not hurting because of the nitrate. however, frequent large water changes are not a substitute for a balanced system. you need to either reduce the bioload or improve your filtration system to handle the current bioload. How many/What kind of fish do you currently have? Also, bear in mind that in a system of your size with lots of coral and an anemone you have the potential for excessive chemical warfare. Running carbon can help with this, as well as the water changes.

[dmweise]

The only filtration I have is my skimmer and a filter sock. I don't have any other type of filtration, though I've been looking for a way to rig up a bio ball filtration canister. My sump is rather small, only a converted 10 gallon aquarium. None of the sumps I bought could fit in the stand.

Here are the inhabitants of 'Little Bangkok':

Tomato Clown (2)
Bicolor Angel (1)
Blue-Green Chromis (5)
Devil Damsel (1)
Lawnmower Blenny (1)
Flame Hawkfish (1)
Sixline Wrasse (1)
Coral Beauty Angel (1)
Horseshoe Crab (2)
White Sand Star (1)
Coral Banded Shrimp (1)
Fire Shrimp (2)
Long Tentical Anemone (1)
Mexican Turbo Snail
Turbo Snail
Astrea Snail

[marshall.read]

seems like your current bioload is too much for your filtration. a refugium would definately help, if you could find room for it. they make hang-on-back style refugiums as well. perhaps upgrade to a larger skimmer if possible. reducing the bioload would help. Any one of, or all three, of these options would help. in the mean time I'd keep up with those water changes to keep things under control until the underlying issues can be addressed. I'd recommend reading here as well:
http://www.wetwebmedia.com/nitratesmar.htm
hopefully this has been helpful.