well its not keeping fish for more than 2 weeks
crabs are holding up well 1 or 2 dead here and there
corals died


setup was done months ago. rocked and sand, left there for months to build up algae, then added fish ect.
salinity at 1.017
tap water was used but left to sit for 1 week +

what i notice is that the filtration should be an over flowing system at the water on top had dead water and all green algae floats there, not sure if thats contributing to the death

any info will be great thanks

People usually invest a lot in making sure their water is the purest that it can possibly be before adding it to a tank, especially a reef, and even more especially - a nanoreef.
Pure water is all the rage, using tap water is the other end of the spectrum.
How does it test? Did you cycle the tank? Did you have an ammonia spike and then it came down to zero? What about nitrite?
Have you had a reef before? More info will help us with where to start giving more advice beyond this.
Do you have access to reverse osmosis purified, and then deionized water? I would start wtih that, if we cover the basics you will probably have a much better experience in the hobby. We're here to help.

i havent tested any thing yet, and i figured with a small tank it will be harder to maintain as its very little water and has to be circulated

what i plan to do (i will post pics tommoro)
i want to bore a hole in the back of the tank so i can have a overflow to another sump in a 5 gallon bucket this way i have more water to play with also with the overflow will create a skimmer action (well so i think )

Is this your first tank?

yes my first salt water tank.

but i worked for my uncle maintaining larger tanks about 60 per month all salt water but all 200 gallon and up and i have seen no issues there and 25% of those tanks i used direct tap water to top up every 2 weeks

Salinity should be around 1.023, PH 8.3, Temp 78-80 degrees. Ammonia - 0, Nitrites - 0, Nitrates < 10. Also, you should be able to maintain these parameters.

You may also want to give this a read

Common beginner questions

Good luck!

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Doc

Dr Hank's 200 gallon Reef Tank
http://www.aquariumforum.com/f46/drhanks-tank-3440.html

What fish have you tried keeping in it? Did you try more than one at a time? It's a pretty small tank for SW fish. I wouldn't put more than one small fish in that tank.

What strikes me is that you have a lot against you: being new to SW, trying to keep such a small tank, no skimmer (I think?), using tap water and not doing any testing. People manage to get by with one or two of these factors but trying all of them at once is going to make it almost impossible for you to succeed.

Try to improve your odds in any way you are able. Test kits, RO water, a good skimmer, a larger tank would all help. If you want to have a small tank read up and ask questions about nano reefs because they are harder to maintain than a larger tank.

Thanks guys, I'll do some read up and post back some results later on and will post pics of the design flaw of the nano cube

Salinity needs to be around 1.022-1.024 and if you're using tap water, at minimum use a dechlorinator and put a bubbler in the water to help get rid of unwanted chlorine. What kind of fish did you have in your tank? Keep us posted

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When in doubt, do a water change.