Sudden Cherry Shrimp Deaths - Please Help

[chico's dad]

Hello,
I have a cycled, 40 litre heavily planted (java moss, java fern, moss ball & anunbias) nano tank with an eheim powerball sponge filter, heater and thermometer. In the tank are 3 guppies, 1 zebra otto and 6 cardinal tetras, nuisance snails and until about 2 weeks ago, a thriving cherry shrimp colony.
I originally had a 30l biorb that I had retrofitted with a sponge filter which had 50/60 CS and then got the 40l tank and transferred most of the shrimp to the new tank once it had cycled and had run for a few weeks with the new guppies and tetras. 
I recently got rid of the biorb (as it is a fishdeathtrap in my opinion) and is now to be a mini balcony greenhouse! So I took the remaining shrimp, anubia (already had plenty of other plants in new tank) and inert black gravel and added it to the existing black inert gravel in the new tank, doubling the depth. So far so good.
Soon after the first water change after adding the old established gravel (about 1" at front to 2" at back now), which would be about 5 months after set up and cycle, I had a couple of shrimp deaths. Unfortunate but didn't think too much of it as thought they had just got in the way of the gravel movements. 
1 week later I do my weekly water change and almost immediately afterwards I have a dozen or so shrimp laying on their backs, dead, all over the tank, gravel, plants, rocks. The fish won't touch them.
I thought this is weird so I left it for a bit and everything settled down, but the shrimp seemed less active or visible. Finally after a week with no more deaths did another water change (the usual 25% or 10 litres) and this time it is shrimpocalypse - must have fished out at least 20 in 2 days.
I think I now have about 10 juveniles left, most of the adults have snuffed it.

General tank info:
0 ammonia, 0 nitrite and between 10-20 nitrate (never really had much ammonia/nirtite even when tank started as used established water and filter and bogwood, plants etc)
As far as I know the water is quite soft here.
I normally do a 10 litres weekly, sometimes fortnightly, water change, leaving the water for about an hour with a quarter cap of seachem prime
I have never medicated the tank with any chemicals, apart from the odd few drops of leafzone
The filter is about 2 years old as have never changed original filter, just squeeze it out in aquarium water until water is fairly clear coming out of it.
Fish are fed flake food or frozen bloodworm daily and shrimp get shrimp food every other day. Food seems to be all gone within the hour.
Temperature is a steady 26C
There is a fair bit of green algae and there was brown algae for a few weeks but this disappeared about same time shrimp started dying
Every water change I deep clean about a quarter of the gravel and suck up a few snails.
Fiosh are healthy and fine
-guppys and tetras never go after the shrimp themselves, not even the dead ones, but sometimes nick their food - 'tis the aquarium jungle after all

Ok so here is what I have narrowed it down to:
-there was some light brownish chunks of fuzzy gunk that suddenly appeared in the water that the shrimp were chomping on, possibly an accumulation inside the filter? no idea what this was but quickly removed any bits I could see.
-pH in the water is 7.4 but nearly 8 out of the tap - maybe I didn't leave it long enough before putting in as seems to lower the longer it is out the tap/treated with prime? 
-apparently the water from the cold tap contains .002ppm copper...is this enough to kill shrimp...? there are still snails, the nuisance kind, in the tank. I am using cold water and letting it get to room temp and then pouring in, but have in the past sometimes whacked on the warm water to make sure it gets to the right temp quick enough. There are also 2 seachem flourish undergravel tabs I put in a few months ago.
-using APi master test kit I get regularly 0 ammonia, 0 nitrite and between 15-20 nitrate (there were still shrimp I did not realise were still living in the then unfiltered, unheated biorb that had readings of .25/5 ammonia and 30 nitrate that I transferred to the new tank when my flatmate noticed there were still some shrimp in the old tank I had missed! so these are hardy little fellas). The nitrate is slightly higher than the usual 10 for some reason-seems between 10-20.

Did another water change earlier after leaving the water with the prime for 10 hours and not having any more noticeable deaths, although the remaining handful aren't looking very active but alive nonetheless....

I have attached a read out of the water from the average of samples taken from the general area too.

Grateful for any thoughts what the culprit(s) might be please. And sorry for the ridiculously long post! 

 

[Chad]

The copper doesn't evaporate so as you top off what is in the tank stays and then you add more with the top off. Eventually that .002ppm builds up and up.

 

[DreamertK]

Prime says that it will "detoxify any heavy metals found in the tap water at typical concentration levels," which copper is a heavy metal but what typical concentrations they would mean I don't know. It also says it shouldn't have any effect on the tank's PH, but it is possible the shrimps got PH shocked. Usually this can be avoided by having very hard water with a lot of buffers to keep the PH the same.
 
Could try switching to RO water for the time being.

 

[chico's dad]

Thanks for the replies -
 
On the copper question, would the same concentration of copper not also kill the snails in the tank - there are still plenty of them with no sign of any dead ones?  Might ask seachem  how much copper Prime can get rid of.  Someone off this forum also suggested I am overdosing the Prime - been using a quarter cap which is roughly 1ml under impression it shouldn't hurt the tank?
 
The water in our area is very soft and I am wary of adding chemicals to water to increase hardness, although I do have a piece of coral that has been in there for 3 years I use to provide some minerals for the shrimp to make new shells in the soft water; my tap water gH is almost zero.  As I am keeping tetraand shrimp am always more keen to have a more neutral pH.  Possible it was pH shock as this was one of my first thoughts.  Can't really afford to get an RO machine.
 
I have been leaving the water out for longer before putting it in the tank and been doing daily 25% water changes the last few days and the remaining shrimp haven't had more casualties in the past 2 changes....

 

[sutantoj]

I lost the entire tank due to ph crashed after I added 2 big driftwoods (newbie mistake). I set up a new tank and added coral for PH buffer and also seachem equilibrium because my tap is very soft, so far so good

 

[DreamertK]

1mL to 40L should be the correct amount. You'd have to put in a few capfuls to overdose.
 
There are stores that sell RO water, like legit RO water not that aquafina or bottled water.
 
As well shrimps loooove hard water because they need that calcium to form their shells. Not the cause of their death, but perhaps the coral would be a good idea.

 

[chico's dad]

Thanks - forgot to say I do have some bogwood too that has also been there for years.  Is it worth getting equilibrium then?
 
The tank is a 40litre so 1ml of Prime would be for a full water change; as I only do 25% changes this is basically a quadruple dose every time.....could this be melting the shrimp?  The java moss has been looking less sprightly recently too.
 
Might get a gH tester to see whether the water in the tank has any hardness thanks to the coral.
 
The store near my flat sells RO water so might give that a try!

The copper doesn't evaporate so as you top off what is in the tank stays and then you add more with the top off. Eventually that .002ppm builds up and up.

 
 

Prime says that it will "detoxify any heavy metals found in the tap water at typical concentration levels," which copper is a heavy metal but what typical concentrations they would mean I don't know. It also says it shouldn't have any effect on the tank's PH, but it is possible the shrimps got PH shocked. Usually this can be avoided by having very hard water with a lot of buffers to keep the PH the same.
 
Could try switching to RO water for the time being.

 
On the copper just found on the seachem  forum that according to seachem a dose of Prime gets rid of 2.6ppm in 10 gallons so I guess it isn't copper poisoning as it would have need many years and no prime treatment to have any copper in it...
 
http/www.seachem.com/support/forums/showthread.php?t=3484

 

[DreamertK]

I'd go with PH swings, which hard water would prevent from occurring as well as leaving the water out overnight. Prime can be overdosed in the case of NH3/NO2 levels needing to be controlled, so that wouldn't be it. Your choice on putting the bogwood in.

 

[chico's dad]

Hi DreamertK - thanks for that - consensus seems to be the pH then!  Will make sure I leave water out longer or find a sustainable and stable way to raise the hardness.
 
Hmmm - what is a good way to raise hardness?  I have a couple of pieces of coral in there that the shrimp seem to snack on.....would this raise it enough?  Or how about the API aquarium salt?
 
Cheers,

 

[DreamertK]

Salt bad for inverts and scaleless fish. I wouldn't go for any sort of powder, but you should test the tank to see how much the corals pumping out. I don't have much experience with it since my water is rock hard already.

 

[chico's dad]

Hi - Yup that's what I thought - haven't been using salt since I got shrimps and tetra for that reason - will get me a gH test to see as pretty sure the water in Edinburgh is pretty much zero gH and see if the coral is raising it to something the shrimp and guppies would like....
 
Thanks!

 

[sutantoj]

what I understand coral wont raise GH, it only raises PH and also acts as PH buffer.

 

[snazy]

Coral contains calcium so it would should raise the Gh some.
As for copper, my tap water happens to contain 0.002ppm too and I pour water straight from the tap into the tank, dechlorinating with prime after so it shouldn't be the issue, unless your water company had some leak or pipe issue raising the copper further. If it happens after a water change, then that what you should concentrate on. What is your current Gh and Kh? If you were leaving the water for a while prior to doing a water change, what did the Ph read? I know it's worse on fish and shrimp if the Ph goes down instead of up, but my tap water is 6.6 and my tank's ph is 7.4 and I do 50% water changes without issues. Maybe your bucket is contaminated, or maybe the tap water is?

 

[Essjay]

what I understand coral wont raise GH, it only raises PH and also acts as PH buffer.

 
 
Just out of idle curiosity, a few years ago I tested a few things to see if they would affect water. One of the things I tested was crushed coral. The method was the same for all objects. I filled two identical tubs with water and put the object I was testing in one of the tubs and left them both for a week. Any difference would be due to the object. I do admit that the exact numbers for the results would not be too accurate, but they did show a trend. With the crushed coral, it was tricky to get the exact coral:water ratio that you would have in a tank and the test was only run over a week whereas in a tank the object would be there a lot longer.
All tests were done with API liquid testers.
 
Plain water - pH 7.4, GH 8, KH 3
Coral tub -   pH 7.6, GH 10, KH 5
 
My tests showed a slight increase in all three parameters over the course of a week.
 
Edit to add: I must stress that a tub of just water was allowed to sit alongside the tub with the coral and I used that for the comparison not fresh tapwater.

 

[chico's dad]

Thanks - so the coral should raise it a bit - I'll keep that in.  They are just pieces of coral, not crushed.
 
On pH.... The water that I left out for a couple of days, this time with just 2 or 3 drops of prime, was about 7.2/7.4 pH, while the tap water coming straight out is nearer 8.  Just did a test of the tank water and the pH is about 7.6/7.8.  And just found another dead shrimp. Think I am now down to 2.
 
Ammonia and Nitrite both 0 and nitrates are now down to 10/15 after the three 25% water changes this week. Temperature stable at 26C.
 
I am however now noticing some dead snails though when I did the gravel clean....but the fish seem fine and healthy still [touch wood!] Its the same bucket I always use that I rinse out before using.  The readings for the area are in the first post, but it is possible there is a copper leak or something...will take a sample to the LFS later too as they refuse to do liquid tests at the weekend when I was last able to go on Sunday!
 
I am going to go and get a gH and kH test later to see exactly what these readings are.