Backyard Aquaponics
A place to discuss aquaponics

I've lost more Mussels and I think it was the cold this time and not the heat as with the first lot.

I noticed the sump water wasn't as clear as it usually is and checked on the Mussels and found them all dead, we have had some very cold days just previous too that and with the fish not eating and the 3 filters I thought maybe it was lack of food in the sump.

I checked one of the Mussels in the fish tank and it was OK so I started to think it was lack of food in the sump and a few days later I checked another Mussel in the fish tank and it was dead.

Then I checked all the Mussels in the FT and only one was alive it must have been the guy I pulled out the week before.

It must be the cold so now I have an approximate idea of their temperature tolerances and if I were too keep them again I would move them from the system when the weather approached those temperatures.

I need to be able too check back on when I lost the last guys due to the extreme heat and know what the water temperature was back then.

I had a computer crash a few weeks back and I have just replaced it and I'm now trying to recover data from the old computer and that temperature information is in the 4 terabytes of data I'm still trying to recover.

How much salt is in your system?
From memory they start to struggle around 2.5 to 3ppt. I have a vague memory of 50% mortality somewhere not much over 3ppt, I can't find the document at the moment though.

Thanks Bodgy,


My system runs constantly at 2.0ppt to 2.5ppt and these guys went into the system in June2014.

It's very hard to find any decent information on their salinity and temperature tolerances and you might be right 2.5ppt for a long period of time could be what's knocking them off.

The temperature swing between day and night here in Melbourne is quite large and the system probably needs to stay salted but I'll try keeping it a bit lower from now on.

I'm only guessing my salinity at this stage but I'm sure it's over 2.5ppt, closer to 3 and the mussels in my FT are still alive.
But I'm sure I read of 50% mortality at 3ppt but it could have been 3.5 or something else if my often faulty memory is taken into account.
2.5 is getting into their discomfort zone but I wouldn't have thought it would kill them all.
Maybe strains from different areas might have variations in their salt tolerance and yours were more susceptible?
I'm no expert on mussels, I looked into it when I was worried about nitrites early on and salted but if they all died I'd still suspect that something else pushed them over the edge.
So I wouldn't blame or discount salt as the cause.
Not much help am I?

Bodgy you've been a great help you've changed my way of thinking, I hadn't worried too much about the salinity because the system had been running at the same salinity for so long and they were only falling over when there were extreme temperatures at either end of the scale making me think that was the problem.

I know the water is fine all my reading are consistent with only the pH varying from 7.0 to 7.2 every now and then, Ammonia 0, Nitrites 0 and Nitrates 0 constantly all at the same levels.

The system is very stable without any variation and as you say the 2.5ppt could have them right on the limit and it's that little extra swing in temperature that is taking them over the edge.