DaJMasta

While electricity in the tank can cause issue, yeah it's normally something that doesn't target a specific kind of thing. Your tests show pretty normal but maybe a little low calcium (not the cause of inverts dying.) If you have a multimeter it's not all that hard to check for electricity in the tank, but while disassembling pumps may be more work, checking any magnets for cracks or rust should be easier and if you find something, maybe that's the culprit. Is there any chance the salinity has swung? Like is it a small volume tank with a lot of top off added at once? I've had trouble with inverts in small tanks if the salinity changes 1 ppt per day, especially for consecutive days. While not necessarily the case, if you suspected some metal contamination, you could run Cuprisorb, Metasorb, or Polyfilter as a means to try to bind up some metals in the system. If you end up sending in an ICP and it shows that issue, especially, but also water changes will reduce levels.

I unfortunately know the feeling, it seems like even when we have the ability to do something we can sort of be helpless. I think freshwater dips are usually fairly straightforward, though I think best practice is to try to pH match the source water (usually adding a tiny bit of buffer like kalk or something, but it tends to be very small and I don't know how much it actually matters). Maybe doing like a 5% tank water and 95% fresh water would be close enough. I think the FW dips are generally not that dangerous for a lot of things, but by the time fish are showing issues swimming or orienting themselves, they are typically in dire straights. Animals generally seem to hide injury and pain pretty well, presumably because in the wild they get singled out as easy prey if they show it, so it's often tough to see there's a problem when there's actually time to address it. While no flukes in the FW dip water likely says it wasn't that, I don't know of what may have been the cause or what could have been done. While there is some stress in handling, I doubt the FW dip made things worse, at least.

You could do a generic water change, and do check your salinity (and calibrate your refractometer/probe to be sure), I think otherwise the things that would give inverts trouble are often only ICP-detectable, so unless you somehow have copper in your water (would also kill corals), I don't know if there's something to check parameters wise. It's probably good to check magnets and pumps in the tank to see if there is a seam and some leeching metals, but it could be an involved process. I only got pithos once but had one or two losses shortly after shipping - I wonder if they don't ship as well as other crabs.

Sorry to hear, it's been my experience that often when something starts to show symptoms of a problem, you either have a very small window to react or it's already too late. In any case, if you're familiar with the forums/information on humble.fish, that is a pretty good community for addressing fish disease and treatment, and may just be a more active place than here. There's also Reef 2 Reef as there are a few people there that are pretty good with treatments and pretty quick to reply. While I don't have any kind of diagnosis for you, one thing I like to keep on hand is methylene blue, as if there are breathing issues/ammonia burn (mostly after transit) on the gills, the extra oxygenation seems to help things a bit, and it's safe to just take normal tank water in a bucket, add a few drops, and let the fish be in there for a while. I've also lost a few in that dip, it's no magic bullet, if it is an oxygenation thing rather than an infection or other stress response, it could potentially help.

Nope, I own a few but none of them have been wet in years. If you turn a flashlight on at night you see all kinds of debris, I don't notice it much during the day and I've got a bunch of bivalves and worms which seem to appreciate it. No microbubles or particularly problematic bits around unless I've really stirred things up. Don't have a fleece roller, but I think it's a similar kind of device. They can still be useful (for use when manually cleaning, for example), and if you have really clear water and glass you will probably still notice the bits they can catch, but I feed plenty and have a pretty high fish load and at least with my skimmer/rock/ceramic media, I haven't run into harmful nutrient issues without, though I also don't chase low phosphates and don't have extremely demanding corals.

I've never run mine. You get some mechanical filtration and some biological at the best of times, but our systems are built around surface area for bacteria (sand, live rock, etc.), so the added sponge is pretty minimal (as opposed to freshwater, for example.) I personally don't bother with mechanical filtration, really, as the ocean is full of particulate and lots of stuff eats it. Not for everyone, but it's been working fine for years for me.

It is possible to slowly work around the perimeter of the foot with fingernails/a credit card and gently pry up a side, when you can get a finger under the foot or so it starts to go a good bit faster. Then you can also just pull the rock in some circumstances, but it seems like this unusual diy gadget does well for people: https://www.reef2reef.com/threads/safe-and-easy-diy-way-to-remove-nems.861213/

I keep the newly settled ones in a basket held onto the side of the tank with a magnet. In it there is a little cover, a little macroalgae, and a little piece of ceramic media that has some aiptasia, since they should eat it at some point. As far as I can tell, the settled shrimp are opportunistic omnivores, so I've just been putting in a little of what I feed the rest of the tank, but I've been adding some newly hatched artemia to be sure and they may be able to do alright just off the biofilm - hard to tell for sure.

A second one settled, this time from the second batch, making it a 99 day settlement. While it sounds like it's skewing down, the second one from the first batch still hasn't settled by day 118, so seems like a good bit of variability. Also, it doesn't appear that temperature plays a huge role - I will see with the second batch, but while the first batch was 24-25C the whole time, the second batch had its 25W heater stick on after a week or two, and while I eventually caught it, it would only push the temps to 27C, so I let it go. A 2-3C difference for nearly the entire duration and the settling times at least appear to be pretty close so far. What's more, the first shrimp has molted 2-3 times already and is nearly twice as long as this second one in its two weeks of being a juvenile. New one:

The first batch had some equipment issues that meant a month in, it was only two shrimp - one of the two has settled. The second batch has maybe 2-3 dozen and should be soon. There could be a third batch another few weeks later - I thought I had collected fire shrimp larvae, but not 100%, and some recent fire shrimp larvae I got look probably different from how they looked. Will have to see when they settle.

A week and a couple days in, the second still hasn't settled, and none of the batch from May 21 have settled at 3 months in. The one that did settle has gained a good bit of color, though, and molted only a week after settlement. It was a big difference in behavior from larva to settled shrimp, but a pretty big difference in behavior from day one settled to day two as well - definitely expending less energy and preferring to hide much more (like the adults.)

I just started them off in the tank water they were collected in then new salt water. I saw a very small amount of detritus build up outside the kreisel section and there is definitely a copepod population, and even a little water cloudiness in the last month, but aside from the film on the surface it appeared mostly fine. For feeding, I aimed to only add enough artemia to be consumed within 12 hours or so - both to reduce the fouling of the water and to keep the artemia closer to their hatch time. I used the disk shaped hatchers for a long time but broke one screen, so eventually I bought a pair of Ziss hatcheries and they have been good and easy to use so far. I actually don't even use a light to settle them - the egg shells float pretty well with modest aeration so I just harvest the main solution until the end where I disconnect the air and get the last bit before the eggshells on the surface. I think the feeding quantity for 50ish larvae after a month or two is like 2/3 of the column of a 5 mL pipette, but this varies with density. For the two larvae in this run, they would never eat through enough artemia for them not to be in the water, so I just fed like 0.5mL or so twice a day to make sure there was food available.

Thanks! It was primarily newly hatched artemia (day hatched to about two days old), but I occasionally supplemented a slew of whatever copepods I had and every couple of weeks added some phytoplankton. Oddly, very few water changes or other interventions of any sort, about 3 over the full duration. The molts would sometimes be visible in the tank, but eventually broke up, dissolved, or were otherwise consumed, and I believe most of the dead larvae were eaten by live ones. Don't think this shrimp got a lot of that, though, it's been only two larvae in this batch since the end of May. Pulled it out, took some pictures, and transferred it into a holding basket in a proper tank. For reference, that is one well in a two well slide, the water is maybe 4-5mm deep so the shrimp is probably around 9mm nose to tail.

This first post is more of a teaser than anything, but after 103 long days of waiting, I have a settled Lysmata kuekenthali! I'll have more full documentation, explanation, and the print files for the kreisel design I used available soon, but for now, a blurry video of the first successful settlement:

The colors are looking pretty good to me, but that can take some time to settle in too - often months to really get all the way there. I think it's a good call to let things grow, in a tank as small as yours (or as small as mine) it feels like when stuff really stops looking like a frag, it's almost too big for its neighbors. Keeping the numbers down will give you some nice bigger pieces provided they do well, and it helps the wallet a bit too