Hatchery Problem

[xnsdvd]

Hey guys,

We just set up a small 7000L hatchery and have been cycling the water for 2 months with sea lettuce and mangroves in the sump. 2 weeks ago we placed a few fish, crabs, prawns, worms, snails and a lobster in to test. All the invertibrates died within about 3 hours of being put in but the fish are fine and feeding. My guess is that there's copper in the water, here's what I've observed so far;

Crustaceans were lying on their sides after an hour and began twitching.

After 2 hours they were completely motionless except for the swimmerets which remained twitching.

Gills stopped moving after 3 - 4 hours.

Oddly enough, all the dead inverts tasted pretty damn good when we cooked them =D

So what are your thoughts?

Specs:

pH: 7.9

Salinity: 27ppt - Not a mistake, we're working with estuary species like Portunus pelagicus, Penaeus monodon, Lates calcarifer, Lutjanus argentimaculatus and Epinephelus lanceolatus and E. coioides

Temperature: 28ºC

gH: 80ppm

Nitrates: 0

Ammonia: 0

Flowrate 15,000L/hr

[xnsdvd]

Just got 2 copper test kits(for accuracy) from Aquamarin, it turns out I have NO copper in there at all. Is there any possible scenario where fish would survive but all invertibrates won't? I'm utterly stumped. Anyway, I've got some photos of the setup. Hopefully that gives you a clue as to what might be going wrong.

See the little milkfish in the corner? They've actually put on weight since we put them in.

New mangrove shoots in the sump.

View from the left

View from the right.

Come on guys, any guesses? Do I need to make offerings to the sea god?

[RushAct]

might be the soil? my guess would be the invertibrates you added makan something from the soil which contains something bad? haha idk

[xnsdvd]

The soil is just aragonite.. is it possible that my water is lacking something instead of having something extra? Hmm...

[spy_i]

are you using plastic container? what is the container made off? there was once an article in Reefkeeping magazine about sump that uses brute cans. causing some unexplained death to LS. Might be interesting to read up on it.

[rockfish]

Hi there!

Shrimps, Crabs and lobsters are very sensitive to water conditions.

Sudden change in the water conditions might kill them in the matter of hours.

Before u introduce it to the tank, it help to acclimatise them to let them adjust to the new water condition.

[xnsdvd]

Hmm... I agree with you on the crustaceans, but what on earth killed the snails and worms? You'd think nerites would do fine in almost any conditions.

[FuEl]

Try some airstones and calibrate the refractometer with distilled water.

[Terryz_]

I am thinking whether is the inverts acclimatized? Mostly they have this problem, even with snails and "worms"?

[xnsdvd]

Calibrated the refractometer, no change in salinity.

Acclimatized the invertibrates(flower crabs this time) with the drip method till the ratio was 4:1 Hatchery water : Old water, still no difference, they went through the strange shuddering motions 6 hours into the process and I had to pop them into the quarantine tank to revive them.

Completely at my wits end...