Good luck with your transfer! Like stated earlier, downgrading is always easier, and you can just litterally take everything from your 90 and move it to your smaller one. You can do it in a day.Simplest way imo is:
* Get your smaller tank situated with its location/stand/etc.
* Move 20-30 gallons from the 90 into the 40
*Attach a powerhead to keep the water circulated while you work with the other stuff
*Get a few 5 gallon buckets (from any home improvement/garden store)
*Fill those with 3 or so gallons each from your 90
*Transfer your corals into one (but keep in mind that if you have any that emit toxins when disturbed, or have sweeping tentacles, that you will have to seperate them in different buckets)
*Move your rock and larger inverts into others (keep any anemonies/carpets/etc. with the rocks)
* Set those aside, and move onto the substrate
* Moving substrate can be a pain in the arse, but doing as much of the transfer as you can, under water, is usually the easiest and not as messy. If you have sand, dont use your hands, LOL that will take you forever and a day.. It may sound funny but I have a few of those children's beach shovels, and they come in handy for sure, LOL.
* Get a gallon sized zip-lock bag, submerge it in your tank to equalize the pressure so that it will open back up, get your shovel, or whatever you choose to use, and start scoopin it in.
- No matter how much water is in the bag, the substrate is far more dense and will sink into the bag.
- Once you have the bag filled about half-way or a little less, take it out and squeeze the sides slighty to purge some of the water so that you can hold it without it spilling.
Adding the substrate to your new tank:
- The last thing you want, especially when trying to restructre all your rock and corals, is a murky tank you can't see anything in... with that said, DONT just pour the sand/substrate in.
- Ever use a beer bong? Know what one looks like? - Ok good, this is pretty similar, go get some clear tubing 1" should work just fine, but yes, you can go a little bigger.. Get a large funnel and stick it in the top, if its smaller than the tunbing, secure it, and seal it red-neck style wth duct tape or another hill-billy fix-all, lol.
- Take the zip-lock you filled earlier, and start to pour your sand/water mix into the funnel.. The water keeps the sand loose and moving, so you may need to manipulate it a bit with your hands as you pour.
- OH YEA - and make sure the other end of the tubing is IN your tank! *wink* yea I have had that blonde moment before, LOL!
You may need another pair of hands to direct the tube around the tank as you pour. Jst keep the tube as close to the bottom of the tank as possible.
Once that bag is empty, return to your 90 and do it again. And don't worry about what gets stuck in the bag - you'r not going to use all of the substrate from your 90 in your 40 anyways, so dont sweat it.
*Once your substrate is transferred, move your rocks in, and place them where you want.
*Next start adding your inverts
*And finally place your corals back in. Be sure to keep them submerged as much as possible, and only exposed to the air for no more than a few seconds.
*Once you have all that in, move your filter, lights, etc. over and hook them up. If you have a lot of "in tank" eqiptment" - situate those before adding any rocks/animals/corals back into the tank (but after adding the substrate).
However you decide to clean up, is up to you, LOL, have fun with that! LOL
Let us know how it goes and post picures when your done - or as you go!
Good point on the coral exposure as well...a lot of people over look that issue. If you're using the same equipment and take the proper precautions when moving the corals, you should be all set.
