[Shana]

I have a small tank of orange shrimp (cherry morphs) that has been having some mysterious deaths. Not a lot, but pretty steadily and I don't know why. They're berrying and breeding steadily and I have babies, but the adults keep dying. The one odd thing that I have found is that something in the tank is changing the water pH and I don't know what it is.

Tank: 3.5 gallon
Sub: Black sand
Hardscape: Spiderwood
Flora: Dwarf water lettuce, anubias, mini pellia, subwassertang, java moss
Fauna: Orange shrimp (10-15?) and ramshorn snails
Temp: 76
Filter: HOB style filter (built into tank), sponge filter
Light: Finnex Planted + LED Light
Ammonia: 0
Nitrite: 0
Nitrate: 0
gH: 120
kH: 80
pH of water in tank: 8.0
pH of water before it goes in tank: 7.4-7.6
WC: I'm doing multiple small water changes throughout the week, probably about 10% of the water three times a week. I rinse out all of the filter sponges at this time.

The only odd thing I can see is the pH. Do you think the pH swing could be causing the deaths? Why is my pH increasing in the tank? I would have thought that if anything the wood and plants would cause a decrease in pH.

 

[theatermusic87]

PH changes gradually through out the day as plants use end release oxygen and co2. Nothing drastic but 0.2-0.3 is normal and not an issue.
Also if your water change water comes straight out of the tap, it can have dissolved gases that drive down phs well. Wait 24 hours or aerate your sample with an air stone and then test your ph

 

[livingword26]

See Above

 

[WaterLife]

The lower pH of the tap water may just have higher concentrations of co2, resulting in the lower pH.
To test, you can let tap water sit for about 24 hours to degas, or add a airstone to the container of tap water to speed up gassing off the co2, then test the pH.

Do you have any rocks in the tank? (could raise pH)

Shrimps only live 1-2 years, maybe they are just old adults?
Are they molting fine?

I really doubt those pH differences are causing the deaths.
Any signs of bacterial infection or any other disease?
Shrimp Diseases and Diagnosis - Shrimp Health & Care - Shrimp Keepers Forum

How long have you had them?
What do you feed them?

Got a TDS meter?
Other water parameters look fine.

 

[Zoidburg]

What about filter media??? Certain types can also raise PH.

 

[Shana]

Thanks for all of the replies. I hope this answers everything.

I'm using water from a 3M water filter system. It's at work, not at my home, so I don't know everything about it but I've been told the TDS is 10-15. I don't have a meter to check.

I tested the pH of my aged water and it is also 7.4 - 7.6, depending on whether I am using my "high" or my "regular" pH drops.

There are no rocks in the tank but there is a piece of cuttlebone a little bigger than a pea that I put in there in for calcium. (Maybe I should remove that?)

I got these shrimp in late January, so there is a chance they could be old. I did think of that. But I started with 12 and now I'm down to about 5 of the original adults and that seemed like a high percentage of deaths to me. They came from a local breeder, not a pet store.

I do see molted skins so it looks like at least some of them are molting fine.

I've never seen any sign of illness or disease that I recognize. I'm a new shrimp keeper so I could be missing something, but from what I've seen they're just swimming around acting normal and then they suddenly slow down and a few hours later they just keel over, kick for a while, and die.

They have been eating algae wafers, zucchini, and occasionally Captain Bob's Frenzy (fish meal, dehydrated spinach, sweet potato, asparagus, and carrots, garlic, Omega-3 fatty acids, pure spirulina powder, vitamin C, vitamin A, vitamin K). I powder it and give them a pinch in the morning. It's easy to monitor the food in this tank because it's in my office and I can keep a close eye on exactly how much they do and don't eat, so I don't think I'm over or under feeding. They do not eat on the weekends.

My filter media is a sponge on the sponge filter and a HOB filter cartridge. I tried to include links to both of those but they didn't work. They're the standard sponges and cartridges. There's also a sponge on the outflow nozzle to baffle the flow, but it is also just neutral foam.

 

[Brolly33]

I think you are being too aggressive with your maintenance.

Neocaridina are notoriously hardy. I have successfully raised them in water from 6.0 all the way to 7.8. I doubt it's your pH that is killing them off.
Cuttlebone is likely the cause of your pH rising, given your 3.5 gal water volume, but your shrimp probably love nibbling on it for calcium. I would leave it.

Shrimp like stable water. 3x a week water changes are likely stressing them out. Slow your water changes down to 10% once every 2 weeks. Just top off the evaporation loss.
With all those plants, you actually could get by with water changes 4x a year and have a very happy shrimp colony.

Sponges in shrimp tanks love to be dirty. They work best that way. As long as water is still flowing, don't squeeze them out. When you do rinse them, rinse only one, to preserve the bacterial colony on your other dirty sponges. All kinds of good stuff grows on them to keep your tank water stable. Also, if the shrimp have access, they will eat the bacteria that grows in your sponge filters. They love that stuff. Reduce sponge cleaning to one sponge squeezing a month (use old tank water in a bucket for rinsing them, not tap water).

For 12 (now 5) shrimp, you are probably still overfeeding. Try a Monday Wednesday Friday schedule. If you feel guilty not feeding, try some of the leaf based food, like Indian Almond Leaves (boil to sterilize then just leave in the tank to grow bacteria for your shrimp to eat). One medium leaf lasts about 6 months in my 12 gallon.

Old shrimp don't seem to transition to new tank water as easily as juveniles.
For the babies, this is the only water they have known, so they are supremely well adjusted, if you can just get the colony jump started.

Last thought. Obvious but I did not see it mentioned. Can you test for chlorine in the water?