Float and dump is something people do - but it doesn't need to be 45 minutes, 15 minutes gets the temperatures close enough. You may be aware, but the big issue is trying to move fish from a lower salinity to a higher one. If the fish are shipped in say, 22 ppt and you dump them into 35 ppt, they will likely dehydrate and die.
I'm not a big fan of the TTM, as it doesn't address the huge benefit of getting the fish into a stable environment and it is very labor intensive, and prone to human error.
Here are my basic acclimation instructions:
A simple acclimation process
The following process is one that should be employed for all normal acclimation of animals from one system to another.
1) If possible, determine the water quality values for the aquarium that the fish will be coming from and adjust the receiving aquarium’s values to a similar range. As mentioned, if the values can be made nearly identical, no acclimation process is even required.
2) The fish must be transported from one aquarium to another in a manner that minimizes additional stress. The fish should be kept in the dark, and supplemental aeration or oxygen must be used for any transport lasting longer than about 30 minutes. Heat or ice packs may be required to maintain a proper water temperature during long transports. If you have control over it, handle the transport container carefully to avoid exposing the fish to any undue physical shock. Remember that losses during transport are always skewed to the very end of the transport time, so delays must be minimized.
3) Once at the destination aquarium, turn off the tank lights, dim the room lights and float the sealed bag in the aquarium for 10 to 15 minutes. This is sufficient to equalize the water temperatures.
4) If you don’t already know the values, check the pH and specific gravity of the aquarium and the shipping water. Long-duration shipments (greater than 24 hours) need to be handled differently and are described below. Avoid any increases in specific gravity greater than .004 units—adjust the receiving tank’s specific gravity to match that in the transport bag.
5) Open the bag, and roll the top in on itself to form a floatation collar. Remove as much of the shipping water as you can while still keeping the fish in an adequate volume of water. Add to the bag a volume of aquarium water that equals 25% of the volume of water in the bag. (For example, if the bag holds 8 ounces of water, you would add 2 ounces of tank water.) The fish is now 20% equilibrated. Wait five minutes.
6) Remove enough water from the bag to reduce it to its starting volume, and now add a volume of tank water that equals 50% of the volume in the bag. Wait another five minutes.
7) Remove water from the bag a third time, again reducing it to the starting volume, then add a volume of tank water that equals 100% of the water in the bag (the bag is now 75% equilibrated). Wait five minutes.
8) Release the specimen into the tank. Most aquarists avoid letting any of the acclimation water enter their tank. If the animal has been released into a tank housing other fish, monitor them very closely for signs of compatibility problems.
Flow acclimation
Some advanced aquarists and fish importers utilize a technique known as “drip acclimation,” where a small hose is set up to siphon water from the main aquarium into an acclimation container. Home aquarists often try to emulate this method but almost always set the water flow rate too low. For example, for one liter of water, if the drip line is set to one drop of water per second, would take 50 hours to reach 90% equilibrium.
A rate of flow of one milliliter per second will result in one liter of shipping water reaching 90% equilibration in 2½ hours, a much more reasonable time frame. Even then, the aquarist must supply supplemental aeration and possibly temperature control during that time.
Special cases
Not every acclimation scenario can be handled by the simple method described above. The following are special cases that may require aquarists to deviate from the regular procedure:
1) During the winter, a shipment of fish may arrive severely chilled. Remove the bags from the shipping box, and then remove any outer plastic bags or paper wrappings and lay the bags in the room in dim light. Do not float the bags in the aquarium yet, as this will reduce proper gas exchange. After 30 minutes or so, the fish’s shipping water will have warmed up a bit and the simple acclimation procedure can begin.
2) Sometimes, bags are punctured during shipment, and some invertebrates are shipped “damp.” In these cases, no acclimation is possible. Just place the animal directly into the aquarium. In these cases, the stress of keeping the animal longer in that state is greater than the stress they incur if simply moved directly to the new environment.
3) Any animal that arrives moribund (not moving or upside-down in the shipping bag) is undergoing peracute stress. Eliminating this stress takes precedence over trying to minimize the perceived acute stress of not acclimating the animal properly. Adding the fish directly to the aquarium as in step 2 is actually the best course of action. Some fish that arrive barely breathing can actually be revived by holding their mouth open into a gentle current to help ventilate their gill chambers.
4) Starfish, sea urchins, octopuses, and some crustaceans are extremely sensitive to rapid changes in pH and specific gravity.
