Excellent questions and discussion for sure.
regarding the water changes, taking all of the water out gets me the most waste export and it does not affect the nitrifying bacteria that are stuck to walls, rocks and the animals themselves which oxidize ammonia. There are nitrifiers as well in suspension that get removed at water change, but they pale in proportion to those located within the massive surface areas found in the curves and notches of the reef itself. THis is also why using UV sterilizers in large systems has no effect on cycling nitrifiers, those can only sterilize what passes through them but will not harm the surrounding bacteria that do most of the work.
100% water changes are ideal in any system, the single best analogy is your car's oil. Imagine pulling up to the station and having them change 20%. 20% helps you avoid algae about 20% as well as a full change would, but in the case of larger systems these giant changes are impractical. I'm just saying they would help a system, not hurt it. When fish are involved you just have to take care to match the params perfectly, I don't have to match them perfectly with these corals, they are tough.
I think the amount of waste the algae uptake in the coral tissues is certainly there but negligible compared to the amount of food I was feeding. If every piece of mysis was inside a polyp I might not have to change the water so much, but you can see the spillage which is dumping a whole lot of nitrogen into the system...100% water changes are the key.
so, in this system, the different between a 20% water change and a 100% water change is literally 3 seconds more siphoning and three seconds more refilling. So, with each water change in this tiny reef model I am illustrating two critical points:
a. the resiliency of reef animals. My temp and specific gravity are never matched perfectly, only generally, and these animals have an innate tolerance to these cycles which is something like the abuse they get on a reef flat in fiji after rain storms (which alter temps and salinity greatly)
b. the fact that 20% changes are not helpful compared to 100% changes in any system, and if it were, oil changes in your car would only cost 5 bucks per quart changed every three months! lol. Of course changing some water is better than none at all, but an important discussion point here is why do 98% of reefs or fish tanks develop crappy algae over time...changing only small amounts still leaves nutrients to sink up in the tank and in time will become liberated back into the system and begin visual degradation of the tank (eutrophication)
I want to also point out detritus removal is a water change's heartbeat. The more detritus you can remove in a change regimen, the less actual volume of water change is needed. When you change water, you are changing out the chemicals liberated into the water column from *stored up pockets* of waste in your system. The water change does not remove these generation sources if you only suck up tank water!! It only resets your water column to 'clean' and therefore it can catch and hold your waste dumps until the next removal. Skimmers also help in this...part of the reason I employ these heavy changes is also because I don't want to strip my system to the bone every time I clean it, I can't, it's packed too much. For the pockets of waste I do have, I need to be taking out as much trash as I can at cleaning time so algaes won't have any food sources. You guys have filters and skimmers to lessen this loading a bit making 100% changes ideal, but not required when paired with good tank husbandry. My reefs illustrate that 100% changes certainly don't hurt, and these mechanics can be extrapolated upwards to the science of larger tanks indeed!
I would also like to point out the difference in water change habits between these two videos. These reefbowls are two different ones. In the vid with the boxer crab and shrimp and all the feeding, that was the tank that gets changed out two or three times a week because I am choosing to feed it heavily to keep these kinds of corals. In the video where the sealed reef tank was there, that reefbowl had corals that didn't require a lot of feeding so that bowl ran two weeks in between water changes, matching what you guys have in a maintenance routine yet only at the gallon level. One does not have to change as often as I do, I just do it to see how much a tank can support.
Hey what did you guys think about the sealed half gallon sps reef that does not evaporate, how nice would topoff elimination be in a hundred gallon reef!! Too much heat though. if you scaled up my system to a normal sized one, your cooling fan would be as big as your house he he
