JettsPapa

. . . and if you're in the Houston area I can point you to some.

I've used at least two brands of pool filter sand that I bought from swimming pool supply stores. I didn't rinse either one. One had a very small amount of cloudiness that was cleared up the next morning, and the other one didn't have any. It seems to be cleaner than the pool filter sand sold at the chain stores.

Welcome to the forum. Topping off with distilled water is a good choice, since the water that evaporated didn't take any minerals with it.

I'm not aware of any algae that would be considered desirable when buying plants.

Have you considered one of the larger rainbowfish, like Boesmanis?

Hello, This may not be what you want to hear, but I would probably just increase the numbers of some of the fish you already have. Tetras and cory catfish are shoaling fish, and generally do better in groups of the same species. Can you list the number of fish you have of each species? You may not have room for more fish.

Drainage isn't under pressure, so clogs are more likely at 90's as opposed to 45's.

As far as I know pipe has always been sold in 10' or 20' pieces (although I believe some oil field pipe is 21').

Assuming that would help with the air pressure, which I very much doubt, I don't think it would be enough to justify the need for the extra material you'll be using (two 45° fittings and a short piece of pipe at each corner instead of one 90° fitting). Plus, more joints means more places that can come apart or start leaking.

I've had decent luck battling algae by adding more live plants (as @Jeff suggested), regular fertilization, reducing light to no more than six hours per day, manual removal, and regular water changes. Instead of every other week, I'd recommend weekly water changes of at least 25%.

Neocaridinas thrive in a wider range of water parameters than caridinas, so unless you have very soft water with low pH they'd probably be your best option.

I have several tanks without filters. The most important factor is to not stock heavily and have a lot of live plants.

My GH is around 16 (300 ppm), and I have a wide variety of fish, plants, and invertebrates doing well in it, so I'm pretty sure that's not the problem. The 40 ppm nitrates is also not an issue. Most fish wouldn't have any trouble with it twice that high.

Shrimp would benefit from the tank seasoning more than fish would, since they often don't do well in new tanks, but it would also benefit shrimp to have some time in the tank to build up a colony before adding fish. I know that's not much help, but it is what it is.

It's not at all odd, if OP isn't human.

They're one of my favorite fish. The best I can tell their reputation as fin nippers mostly comes from people keeping them in too small groups, or in tanks with inadequate hiding places for them to retreat to if they feel threatened. In either of those conditions they can feel constantly stressed, which may cause them to be aggressive when they otherwise wouldn't. Four isn't enough. I'd encourage you to get at least four more, if you have room for that many, or re-home them if you don't.

Frogbit does the same for me. Red root floaters, on the other hand, die a horrible screaming death.

I'm of the opinion that netting fish out of the tank, moving them to a temporary container, and then netting them again and putting them back in the tank after you're finished stresses them at least as much as, and probably more than, just leaving them in the tank.

I wouldn't say you're being paranoid, but since you said you have MTS I doubt very much that you need to be concerned. Besides, I won't say it never happens, but I firmly believe that the danger of toxic gases building up in substrate is often exaggerated. I have a half dozen or so tanks set up with a mixture of dirt and dry cow manure capped with 2" of sand, and bubbles come up through it for months after setting up the tanks. The fish, snails, and shrimp haven't seemed to mind.

If you will re-mineralize then neos would be a good option (they do well for me, and my pH is the same). Mine stay outside in tubs year-round, even with a thin layer of ice over the top for a day or two.

No.

There's nothing to be afraid of, especially if you're looking at neocaridinas. What's your water like?

Have you checked the market and see which plants there is a market for?

It's been 15 hours since you posted, but I'll bet they are eating it.

I can only answer your last question. No, one shrimp would not cause an ammonia spike in a 15 gallon tank.