This tank will likely only be up and running for a few more months, as i am likely to need to move when summer arrives. I have a few important take-aways from this experience that I want to share. Obviously I had a lot of fun with the tank, and I would do it again if in the same situation as when I got it, which is to say that I had plenty of space and new I would not be moving for a long time. Here are some things I have learned from the experience:
Positive points (which will be more concise because they are pretty obvious and don't require explanation):
- More space = opportunity for a more diverse ecosystem. Interesting things will emerge that simply don't take place in smaller bodies of water.
- More water volume = more resistance to freak accidents involving nutrient spikes.
- More space = a potentially wider range of interesting animals.
- Sumps add to stability
- In-sump skimmers are great filtration and have NOT starved out my filter feeders. My filter feeders have flourished with a big skimmer attached.
Negative points:
- There were and still are parts of the tank that are effectively off-limits to me due to my arm length. Even climbing up on a stool and using tongs doesn't 100% solve this.
- When equipment fails, it costs more to replace. Bigger tanks require stronger pumps, which cost more, and so on. The usual things of lighting, power heads, and so on have failed at about the same rate I've observed for the same stuff on smaller tanks. In my cases I don't believe it was poor maintenance in any observed cases either; things just punk out sometimes, either randomly dying with no apparent cause or with an obvious culprit like power fluctuations (everything is surge protected, but some equipment doesn't seem to handle brown-outs very well).
- My sump came with two major downs sides:
1. Top-offs: the sump is a big open-topped area that creates a lot of evaporation. I have to add at least a whole gallon of RO every single day - that's the sort of top-off neediness that is usually associated with tiny tanks. If I were to skip it for 2 days, the sg would be through the roof. If I was going to keep the tank long-term I'd have to invest in an auto top-off system, but these have their own problems such as flooding as a failure case (which can also kill animals if it drops the sg too fast - I've heard many horror stories of this).
2. Overflows are a great way to sump a non-drilled tank, but they introduce more points of failure. Mine has always been very reliable for very long periods of time, but if something is going to go wrong, like an animal somehow getting inside the siphon tube, it goes wrong really fast and has to be caught and addressed rapidly to keep the system ticking over smoothly. For example: one day I found a large hermit crab in the back chambers of the overflow spending its time dismantling the siphoning backup system and pushing the siphon tube up. I still have no idea how it got back there, but finding that somewhat shook my confidence in the system. I am also aware of cases in others' tanks of anemones and corals blocking up drains and overflow tubes, although it has not happened to me personally.
If/when I move, I think I will be scaling back to the nano range and doing more primitive, fairly self-contained tanks (i.e. no sumps) with either hang-on or canister filters for using chemical filtration media instead of skimmers. Or I may go the sump-in-the-back rout like biocubes have; I've really liked the way my fluval specs work, which are similar. Either way, I don't think I will be doing a traditional below-the-tank sump again for a long time to come. There are a few reasons for this, all of which are basically related to changes that will be taking place in with my job and living/home situation:
- I need something that has less possible points of failure, particularly where water leakage is concerned. While my 55gal has never had a complete floor-flooding disaster, there have been small overflows while I've been switching things on/off for maintenance and there have been a few other close calls I would have preferred to avoid. I also really need to be able to go to bed and not wake up at 1am wondering if that sound I'm hearing is my neighbors taking a shower or my sump spilling over due to another mysterious crab in the overflow.
- I will likely need to be able to travel for a 2-4 days periodically without having someone to look over the tanks. Right now, my 20gals could actually do that without a hitch. My 55gal definitely couldn't due to the sump-induced evaporation rates.
- I need it to not be an ordeal and a half if, for random home repair-related or similar reasons, I need to dump everybody in a bucket, drain the tank, and temporarily move it to another place. Small tanks pretty obviously beat out large ones for this. I know from past experience that I can do this with a 20gal in an afternoon quite easily without having an unstable mess. In contrast, it will take me at least a whole day just to get critters out of the 55gal when I need to break it down to move.
While keeping the 55gal, I've had two 20 gallons running on the opposite side of the room that have served as a good comparison for stability and maintenance stuff. When not overstocked, I have actually found my current 20 gallons to need far less maintenance overall than my 55gal now that it's sumped. Evaporation is also a lot easier to control on those tanks and the amounts they require for top-offs are currently microscopic compared to the sumped 55gal. And, short of the tank shattering, there is also a lot less risk of water getting onto the floor. So, while I loved my 55gal as an excursion out of the nano range, I think it will have to be back to smaller things for me later this year.