Tank Capacity

[tbone38]

I've got a 125 gal. tank, with a 125 gal. refugium set up. Recently I added two more fish to the system (as well as two new pieces of coral). I'm wondering what the total fish capacity of my system is...the tank has been running for about 18 months with no major problems. I've recently added lights and am running at about 6w per gallon. In my refugium I have a clean-up crew, some macro algae, but no fish. Do I factor the water capacity of my refugium into the total gallons of my system? In my main tank I currently have:
Powder Blue Tang
Lawnmower Blennie
2 Percula Clowns
1 Lyretail Anthia
1 small Mandarin Goby
1 Foxface Rabbitfish
1 Rose Bubble Tip Anemone
Assorted Coral, both hard and soft
My filter system consists of 2 canister filters, a protein skimmer, and a uv sterilizer in my fuge. The overflow boxes from my main tank drain into a pile of lava rock, the water then moves through the macro algae and is pumped back to my main...water changes consist of around 30 gal every two weeks.
If anyone has a word of advice, I would appreciate it.

 

[rldavisou]

The foxface is not generally considered reef safe, but you may have gotten lucky and have a specimen that doesn't nip at your corals. It's a game of chance, really.
Watts per gallon is an outdated way of thinking about the appropriate level of lighting for a tank. However, since you said you have 6 watts per gallon in a 125, that gives you 750 watts, which is difficult to do without T5's or halides, so I'll assume you have one of those two, which is an excellent lighting choice for your size of tank.
Now, on to your more pressing question of stocking. It sounds like you have a pretty good setup. How much LR do you have in there? If you put at least 125 lbs of LR in your display tank, you're fine. If you put 125 lbs in your DT and even more in your fuge, you're better than fine. If you don't have at least 125 lbs in your DT, add some more, especially for that mandarin. What kind of sand bed are you running in your fuge?
You can pretty much keep stocking a tank until you see a rise in toxins in the water (ammonia, trite, trate, etc). When you see a rise, you're done stocking. If you run 125-150 lbs of LR in each of your tanks and a DSB in your fuge, that's a LOT of biological filtration. You'd be able to stock your tank much more heavily. That being said, I should add that SW fish are not like FW fish. SW fish need MUCH more room to roam and swim. Pay attention to how your fish act, and make sure that you're not just cramming a bunch of fish in your tank just because your filtration system can handle it.
It sounds like you're doing a great job, and have a well-planned system. Post some pics, we'd all love to see 'em!

 

[tbone38]

Thank you so much for the response (and kind words). I feel like I'm probably done with fish stocking, I really don't want to upset the apple-cart at this point. I have approximately 125 lbs of LR in my main, and some tonga branch (approx. 15 lbs) in my sump. The substrate in my fuge is thick, about 6 in. (deep) of live sand between two patches of lava rock. I used live sand as substrate in my main. I can't remember what the brand is, but it is the fine reef sand that comes in 15 lb bags. The lighting I am using to get to the 6w per gallon is two Coralife Lunar Aqualights. Any additional suggestions would be appreciated...reef tanks are an on-going learning process.

 

[ophiura]

I agree that there is more to stocking, IMO, than rules (inches per gallon) and water quality. Fish behavior, such as territoriality and space needs should be considered as well. You have a great "keystone" fish in the tank that will be a stunner and big (the powder blue). I would not risk the stability of the tank, and the health of that fish, by possibly greating issues with stress (overcrowding) or water quality.
IMO, no, you do not consider the volume of the sump in overall "inches per gallon" stocking...because fundamentally the issue is the available space to live in, not the water volume overall. You don't really have 125g in the tank if you have rock.
If you want to do a reef, this is another reason not to do a "max" stocking on fish.