In all the time I’ve been reefing online I know of about four tanks that did the sealed approach and they’re all under two gallons. The one I had for a few years was half gallon.
** I’ve never seen it done at the normal size levels but if you did, that’s article or post gold. There are no sealed reefs in reefing above 2 gallons, or any running currently. Even PJ reefs mini reefs, which are stilled non motion micro reefs with extreme evap restriction, have a pinhole in the fitted lid for the least exchange required to keep a system going... it’s not sealed, but they’re the example of mass testing of the concept as he’s sold probably a thousand of the models online.
We know that biology upscales and downscales 100% between a thousand gallon reef or a half gallon one, that’s why tabletop acro grew into the classic shape in my tiny tank...biology of reefing can be downscaled or upscaled. There is no physical reason other than heat retention if any, you couldn’t make a larger tank behave as a sealed model and depending on your required fish bioloading, and sandbed choice, because these two aspects are your largest 02 command in any reef tank, I bet a large one could run a month or months without being opened up just fine because time will upscale along with dilution. But you’ll be feeding sometimes or you’ll be adjusting things, perhaps raising the lid to access the tank to hand garden OUT some new growth new tank green hair algae etc, all those will be o2 addition and co2 escape refresh events and should keep it running just right. I’m going to find you some threads to set you on the discovery path, let’s brainstorm how to upscale that into full sized reefing trial for sure it’s discovery gold. Even if we don’t choose to finalize it, these brainstorms here might set anyone on the path to upscaling this weird aspect of reef tanking
Talk about smashing of rules
a reef tank is certainly not required to be topped off at all, that’s just how some people (99.92%) choose to run them, heh.
Links below, and here are my recollections about challenges we’ll face after building sealed reefs for a stretch of time between 2003 and 2005:
-The sealing lid if done right is an -inner diameter- seal. Can’t just sit on top and be pressed down... Salt creep will be a massive challenge if the lid isn’t a true fit and pressing from the inside lip of the tank all the way around the tank in some sort of gasket scheme. You’ll have to play around with an empty tank, water, and lid schemes to work out just the part, and this is the only hard part the way the biology will respond is totally predictable. Once you got it down cleanly and it runs two weeks with no top off or so, you’ll know how the salt creep expresses, if it’s manageable, and building the tank inhabitants is simply start w common live rock and easy corals and no sandbed is my recommend, or, a sandbed so thin you can clean it or exchange it occasionally to keep detritus out of this system
Detritus matters here says the guy arguing daily on the “is detritus as bad as it’s made out to be” thread. Fish and detritus, the sandbed by extension, are 02 competing design aspects as the massive stores of heterotrophic bacteria that detritus supports can wreck a sealed tank although you’ll have dilution to assist. Fish and tiny benthic animals from live rock ARE your 02 meter, if they’re swimming / being benthic as normal, in the morning hours specifically, then your tank is in balance. If they’re migrating up top diurnally then you know to drive the plant pump system much better to find balance before we invest in $ fancier purchases as the reef matures
-If done right your sealing lid will be totally condensed all the time with water droplets. This diffuses light. In a half gallon reef any light you use isn’t affected by that as they’re all ten times too powerful anyway...you’ll have to PAR meter verify some of the readings around the testing tank or just keep corals up top for a while as you intuit the workings.
-heat retention is the concern of the day but today’s tech allows for much better workings than I had in 03, I had a fan the size of a house, relatively speaking, to cool my halfer 24x7 I don’t know if you’ll need a chiller, no ones ever done a large model to see.
We make sealed systems work with a combination of plant works and time in between lid lifting as the actual but delayed gas exchange that all reefs require. We just allocate the timing differently than other reefs, I know an internal divided refugium area will work per the link below, but I don’t know what’s most efficient for your needs, an algae scrubber system that’s pump and not air driven, since air requires a positive pressure vent? Not sure, have ta experiment with your plant engine but it’s not super critical as occasional lid venting still balances things out. We leave a small air space inside the tank vs filling water up all the way for a tiny atmosphere area above the water line.
https://www.reefs.org/forums/topic72558.html
Donnie’s 2.5 sealed
https://www.nano-reef.com/forums/topic/264442-my-next-project-a-25gallon-pico-reef/
I don’t dose with c balance anymore and we probably wouldn’t strive in today’s reefs for constant 10-12 alk levels so don’t include that part lol / hindsight
***this one w be considered tip of the year for anyone considering sealed reefing and it has to do with your lid seal approach. I’m telling you saltcreep is a challenge, but this is what I’ll do on sealed pico #2 one day when I get around to it: make meniscus controls in place up under the lid****
Saltcreep is an expression of capillary wicking action around the lid in a sealed tank. Even if you stop the water line a half inch under the lid seal, at the corners the water surface tension has two surfaces to grip to, and it will curve up at the corners of the tank and deliver tank water right to the corners of the lid that is sealed. It’s hard to see in action but the white crust is the proof. Capillary action begins and the lid will have salt creep around it’s perimeter and you’ll hate it, but I think this can be beaten.
I envision a small plastic lip that you silicone carefully around the entire perimeter of the tank, perhaps a couple inches below the lid, and the real water line is kept below that buffer strip not the actual lid! This makes the meniscus action work on that new lip, but two inches above that is the real lid, and no meniscus touches it now. Seal that pre lip really good using acrylic strips, any creative clear plastics you can fabricate into place and I think that will stop your guaranteed lid creep issues.
Lemme know
B
A sealed full size reef has simply never been attempted it’s not reviewed in any printed materials anywhere, no university has ever done one, doesn’t exist online in any search engine, and it’s honestly not that hard to do. Hard to say one is truly covering new ground in reefing, well that’s new ground for sure.
