new tank, found a crab

[glassman]

i set up a 55 gal tank 6weeks ago, filled a 1.5 thick layer of crushed coral and 30 lbs of live rock, waited 2 weeks and added 25 lbs of live rock. another 2 weeks and i added 12 lbs live rock and a snail (what the hey). i went out of the country for 2 weeks and when i returned i noticed a dark brown crab crawling about. it's about 1.5" x 1". when i turned on the lights and started making a racket, he burrowed into the coral to hide. he has since relocated somewhere at the base of some rock (i can see where the crushed coral is moved around). from what i've read on this board, the general consensus seems to be to remove him. i was wondering if anyone had suggestions on how and what to do with him.

[Brooke]

Hey glassman!

Welcome to TRT. Check this thread about crabs:http://www.thereeftank.com/forum/sho...?threadid=6982

I would definately remove the crab if at all possible. If you just can't kill it, then put it in the sump or in a small 5g tank.

A lot of people have banned critters in the sump.

You might want to rethink having crushed coral as a substrate. It tends to trap detritus which can contribute to increasing nitrates. Having a deep sand bed of small sugar-grain (oolitic) aragonite does a much better job of "filtering" the tank. Do a search for DSB (deep sand bed) and you will find lots of info on them.

HTH and again welcome!

Brooke

[glassman]

hmm. i appreciate the advice. i may leave the coral in for now just to avoid the additional purchase im not sure what to bait a trap with, i suppose it may have to wait until i have the chance to return to the pet store and purchase (grrr) bait. i don't want to kill the crab, just seems unfair. unfortunately i don't have a small tank, and i don't have a sump either. i have a fluval external filter and two powerheads running near the top of the water level. they are sitting on top of tubes which run to an undergravel filter; however, the water flow is currently out the powerheads and not down the tubes (should i reverse them?)

[FishDaddy]

Hi glassman,

Good to have you with us!

The glass "trick" shown in the link in Brooke's post usually works well. Such crabs are predators and need to be removed as soon as possible.

What are your plans for the 55, reef or fish-only?
If you are planning a reef, I would suggest re-orienting your filtration setup. I have been where you are. My 55 was originally setup with LR and a Magnum Cannister filter with bio-wheels. I pulled the cannister, coarse substrate, got a skimmer, and the tank has done well for over 3 years now.
IMHO, even if you don't go with a DSB, you have sufficient LR for a reef setup and would be much better with a good protein skimmer instead of the UGF and powerfilters.
Dick

[beach bum]

Yes, crabs are opportunistic, omnivorous, occasionaly aggressive predators, but I like them! They may take a bite or two of your small fishes, or they may not. Having the diversity of crabs, stars, worms, shrimps, etc., makes it more fun for me.

FWIW your UGF and canister filter are really not necessary since you have almost 70lbs of LR in a 55g tank. The canister can be handy if you want to run carbon or some other filter media occasionally though. Live Rock IS the biological filter, as will be the substrate eventually. Yes, even a CC substrate.

chris

[glassman]

well, i know how useful message board advice can be if it is heeded wisely. it seems that the general opinion is that my setup should be rethought in order to optimize on the reef that i want to have in the future. does anyone want to give me a brief synopsis on what an appropriate course of action would be? i'm gathering that firstly i should remove the LR, syphon out the water, dump the crushed coral and remove the UGF. i should then put in a sand bed (with 100# or more of LR would it still be advisable to put in a DSB?) then refill with water, dechlorinate, buffer ph, salinate etc. let water clear, reinsert LR (how to store in the meantime, should i syphon the water out of the tank into the buckets of LR until they are put back in the tank?) then put the powerheads back in (maybe towards the bottom of the tank instead of the top?) and of course institute a sump system instead of the canister filter i had? as you can likely tell, i have a great many questions but i would like to get this done right, i have such big plans. i don't mind the work if it's entirely necessary, but to be honest i don't have the experience to know what is and is not entirely necessary. anyone who has time, i would love to hear your suggestions on the matter. please if you would direct me as well to clear easy instructions on how to setup a sump. i would ask the pet store guy but . . . well, you know. that's what got me where i am now. breaking it down into the most elementary of terms would be helpful.
p.s. i thought i posted a reply to this already, but i don't see it anywhere. if it was accidentally posted in the wrong location in some other thread, forgive the misplacement.
thanks for your advice.

[Brooke]

I'm not quite sure what the best method is...but since you don't have any livestock in the tank...except the snail, you are in a much better place than most to start over with better (less) technology.

Get some 5g buckets or a couple 20g rubbermaid containers. The rubbermaids should be new and well rinsed with water (little or no soap).

Siphon off the tank water into buckets or rubbermaids. Place rocks in rubbermaids. Add a powerhead to the rubbermaid for heat/circulation.

Siphon off the rest of the water. With a big scoop, place crushed coral in buckets. Remove UGF, etc.

Add new sandbed. you might add 1-2", then add your rocks, then add an additional 1-2" of sand to help stabilize the rockwork. (Sometimes it is easier to aquascape with water in the tank.)

Add the water back from the rubbermaids and get circulation going again in the tank. The tank will be cloudy for a few days. Critters from the rocks will move into the sandbed. The rock and sand will act as your filtration.

HTH....there are lots of ways to do this. YOu might try searching old threads. Make sure you have some new pre-mixed saltwater ready to go. I"d have at least 25 gallons.

For general knowledge on keeping a SW tank, check out our book recommendations: www.thereeftank.com/books

The Conscientious Marine Aquarist is a great place to start!

Brooke