Two Salty questions to ask

[thePractce]

Hello experts,

I have just came home from crabbing today, and caught a whole bunch of small ones(unfortunately) but i thought were very cute, i wanted to keep a piece of two however, i released them because i don't know a thing about salt water aquariums(I'm a crayfish person)... so Anyway, i have a 1.5 feet tank lying around and i thought (lets make a for fun salt water aquarium No live corals,No fancy fishes. just crabs,rocks,sand and salt water)

So the questions are:

1) Can i use the water,sand and rocks where i caught the crabs from in the Aquarium ?
2) Is there a Cheap filter system of some kind you would recommend ?
3) Is this a stupid idea considering the fact that i'm not serious (if yes,Don't hold back but i would appreciate reasons)

Thank you in advance for sharing...

[cdckjn]

Actually, if you catch stuff from the beach, in terms being not destroying the envrionment, it is not advisable. But since you done that, yesm you can collect some rocks from the beach, water from deeper now, have a Overhead filter and run the water and you should be able to maintain the ecosystem for about 2 weeks, you would then require a water change (at least 50%). you can feed the crabs with some prawns meat - it should be fine. But for a long term it is not possible and the crabs then to survive with the water mving (in nature there is at least 2 tide changes per day (high-low-high tide timings) which in our aqaurium, it is impossible to do unless you have compicated pumping system to fully empty and fill the tanks.

[planted86]

minimum use a canister filter if you really want to keep them.

don't take home the rocks u found on the beach. firstly, it will destroy the environment if everybody starts to take rock home. and you will not know what kind of nasty things are inside the rocks. and if you want to collect clean water from the sea, it must be at least 20m below sea level. and i don't think singapore water is clean anyway.
if not, best that u buy synthetic salt and mix the water yourself and aclimatise them using drip method.

for wave wise, it is not complusory to to mimic the nature tides. but u can create flow by using wave makers.

[thePractce]

Well, actually i planned to return everything to where they came from after i get bored... but since it's a high chance they might die under my care, i think it's best from me to drop the idea.. Thanks for the tips but i think i'll stick to my freshwater crayfish until i'm ready for a salt water aquarium... After all, i'm still in secondary school..