Some LESS obvious issues that most people DON’T think about and how to address them:

Humidity: This becomes a huge concern the larger you go. My current tank evaporates almost 20 gallons a day. This is with no fans or active evaporative cooling. I deal with it in two ways. One is that I have a chiller and as such, evaporate a minimum amount. 20 gallons may not sound minimal to you, but if I had fans blowing on the sumps I would probably have double that amount. The other is that I have a room fan that vents outside and kicks on when the humidity in the room is over 40%. Other ways to deal with it include having your own AC unit for the room, or just waterproofing and sealing the room so that high humidity isn’t an issue. Mold is a serious concern and should be treated as such. A normal room running at anything over 50% long term is simply not healthy at all! Mold will form fairly quickly in a warm humid environment - ask Ryan, a.k.a. Servo to tell you about his last prop setup! Even with the precautions I’ve taken, I still painted my fish room in boat paint, which is totally waterproof, so there will be no wall damage.

Water changes: Unlike a small tank where a 20 gallon Rubbermaid and a small power head and heater were all you needed to perform a water change, water changes become a big logistics issue on a big tank. I change about 90 gallons of water every couple of weeks on mine. I made water changes a breeze by I simply turning two ball valves to drain the sump and then flipping a switch to put new saltwater in. I have it set up so that I always have 90 gallons of saltwater going all the time. I purposely planned that. If you don’t have space dedicated for that, you will need to plan something on wheels, or something similar. This is one of the most overlooked and important differences. Know how you’re going to do water changes and minimize the effort they take!

RODI Unit: Depending on your water pressure and how big your tank is, you may have to consider a commercial type RODI. I personally selected a Merlin unit from GE that can take 700 gallons per day (GPD). This allows me to never worry about having enough water. If I had a normal 100 GPD RODI with normal water pressure, its actual output is 60-70 GPD. Let’s assume that it does 60 GPD and I want to get 90 gallons for a water change. I evaporate roughly 20 GPD, so it would take me over 2 days to get that much water. If I had to change 20% of the water after an interceptor treatment or something similar (for me that’s about 120 gallons), it would take almost 3 days of planning. It also leaves me very little room for error if I need to do several water changes because something happened or I am just in trouble. It takes so long to make water that I couldn’t recover (Steve Weast of Oregonreef.com, who had one of the nicest tanks ever, just suffered an incident that could have been avoided with a large RODI unit). While this is by no means required, I wouldn’t be without it.

Controller: In a small tank, these are often overkill and insurance, but in a big tank they become essential. The sheer number of timers required by lots of lights and pumps, etc., make a controller worthwhile, to be honest. They also provide really essential functions like cutting the lights off in an overheat situation, controlling the CO2 input with pH, controlling the heaters (nothing is more use-less then a temperature reading built into a heater) and chiller, and so on. I consider an Aquacontroller or the equivalent absolutely essential in a large tank.

I could talk about this for days, as I’ve barely touched the subject but this is a newsletter and not a novel. I’ll leave with my parting thoughts on big tanks. I often get the question “is it more work?” and the answer is yes, but not near as much as you think! On my 135 gallon, I spent around 3-5 hours per week maintaining it. I spend roughly 5-6 on this tank that is over 4 times as large when sumps are included, so the incremental is really not that bad at all. The other thing I’m asked about is about starting tanks. Everyone always says start with the biggest you can, it’s more stable, etc. etc. While this is very true to a point, I wouldn’t recommend any newbie to just jump into keeping a massive tank. You really need to stay on top of things and, while it is more stable, any problems are big problems and any issues take longer and more effort to correct. So, while I love my huge tank, it is a major commitment of effort and dedication, but honestly it’s not much more on-going commitment time-wise then a smaller tank. Wallet-wise - well that’s a different story. It is expensive. More expensive to start, more expensive to run, more expensive to maintain - but it’s also much more fun!

So: PLAN, PLAN, PLAN! Make sure you are prepared and you and your tank can thrive! If you would like to see my 450G adventure, visit http://www.reefcentral.com/forums/showthread.php?s=&threadid=694606
There are many great ideas and threads on the Large Tank Forum at RC, located at http://www.reefcentral.com/forums/forumdisplay.php?s=&forumid=252

Feel free to pm me with any comments or questions or better yet, post it on the boards!