Algae will not go away!!!! And snails, too!

Question

Images, regional, and general info:

Image 1: Strands of dark-green algae are attached to the bottom and floating in the air; algae all over the plants.

Image 2: Over-rich substrate? When I hold the evacuator on the substrate floor, it sucks up a ton of milky mud, which to me says I potentially did not wash this well enough

Regionally, we draw a water from a lake that has a major problem with algae; so, perhaps algae spores are coming in from the tap? I have been considering pre-filtering the water.

I am about to throw the tank away (as the top answer suggested) because I have worked on this problem for over a year and gone so far as to scald the tank and re-stock everything. Nonetheless, I am willing to put in one last great effort and pull out all the stops so please let me know if you have a solution (less extreme is better, but I thought maybe the algae spores are in the sealant so I can't even give it away because I would just be giving someone else a problem).

Hardware info:

Lights: 6 hours (on timer) white LED lighting [I cannot find the manual, but I think it's 80 watts (could be 50, could be 100)]. There is a blue-light (night mode) setting that I never use.

Volume: Using a a 50-gallon freshwater tank.

Filters: Penguin Bio-Wheel 350 multi-stage filter; REMOVED AAUV24W burned out 3 days ago--removed it. That's the one I use on the 10-gallon tank that I use if fish need to go into isolation.

Heater: EHEIM 150watt aquarium heater.

Failed CO2 Injector: The CO2 diffuser got clogged with algae and broke a few months ago.

Thermometer: Also have a glass mercury thermometer that is not compromised.

Top: There is no air-tight seal.

Problem:

• Algae grows all over my aquarium (plants, equipment, rocks, glass, you name it).
• And tons of snails!

How I treat the tank:

• I think the substrait is Ecocomplete Carib Sea (which might be too rich).
• About 12 fish are in there (one Rafael catfish, one Chinese algae eater, 2 guarami, 2 swordtails, 2 platies, 5 serpie tetras, 1 neon tetra.
• I change about 1/4th of the water every week, usually drawing water from the bottom, and 3/4ths of the tank if a fish is ever sick.
• pH ranges from 7.4 (when the water is changed) to 7.8 (when I scrub the algae off the walls).
• Rocks, toys, and gravel are scrubbed diligently and set at a rolling boil for 30 minutes prior to being added to the tank.
• New fish go into my 10-galon isolation tank, which is much cleaner, for about a week, and then adjust in a bag for a while before being added to the tank. We don't get a lot of new fish (anywhere from once per 2-3 months to once per year).

What I have tried:

1. Moved all fish out, moved it to the garage, cleaned every nook and cranny multiple times with bleach, let it completely in darkness, replaced all equipment, new materials (soil, gravel, rocks, housing structures--boiled it all for 3 minutes per item, first). Failed.
2. Treatments. Killed all the plants and probably some fish. Failed.
3. Moved from fluorescent to LED (seemed to make it worse). Failed.
4. Moved the whole tank away from sunlight (may have slowed it down, not sure). Failed.
5. Have always been sure not to over-feed the fish. Failed.
6. High-volume bi-weekly water replacements (3/4ths of the tank). Failed.
7. Adding a very small amount of bleach to the water--the fish surprisingly did fine. Failed.

What I have not tried:

1. Pre-filtering the water.

Question:

• I am legitimately at my wit's end. What should I do?!
• I have to get rid of the algae! It looks like a toilet!!! How can I make it stop!? And these darned snails, too!?

Answer 1

Clown loach fish is known for Snail control. Practically any loach should do. I have used them in past with great effect. Also I have always kept two bristlenose plecos to control algae in my 55 gallon freshwater tank. I have tried chinese algae eaters before but they are too territorial. Give these two fish a try. Natural way to control things instead of trying out equipment or manual labor.

Answer 2

Note: This answer is based on the OP's original questions about an unfiltered 2 gallon tank, prior to heavy edits that changed the question entirely.

Solution: Give up on this tank and learn how to keep an aquarium.

You have a number of bright red flags in your post that indicate you didn't actually do any research on aquarium keeping before starting one, with the brightest of them being that you described this as "about a 2-gallon freshwater tank" with enough fish you can't actually track the number. That is wildly overstocked, and overstocking is the main source of your algae.

If you want to use the 2 gallon tank, you can look into "planted nano tanks," which typically would only host a few shrimp or snails and no fish. They aren't particularly easy to keep, however, so expect a lot of failure as you learn.

The next red flag is that you make no mention of a filter; if you're keeping any amount of fish, using a filter to clean the water between changes is vital. You're overstocked, which is making your water very dirty. Without a filter, that dirty water is just getting worse and worse.

You also never mentioned anything about cycling the tank. It takes time to properly cycle a tank, and trying to cycle a nano tank like the one you're using is very difficult. Proper cycling is critical to proper aquarium care; it helps introduce and encourage the growth of the beneficial bacteria that help keep the water clean and habitable for your fish.

You planted your tank. Plants tend to bring in snails. If you wish to continue with a planted tank, remove as many snails as you can during the cycling process, and continue removing them until they stop appearing. By removing them quickly, you can prevent them from reproducing, and eventually they will die off, but it's not a quick fix.

You didn't mention actually cleaning the tank. Just changing the water isn't cleaning it; you need to vacuum non-planted areas and remove algae from the glass and decorations mechanically. A number of tools exist for these processes; for my small tank (15 gallons, overstocked due to containing livebearing fish) I use a magnetic cleaner and new toothbrush for the glass, and a new dish scrubbing brush for the decorations. Clean them in the water removed from the tank to avoid removing the beneficial bacteria as much as possible.

Your best path forward, in addition to taking some time to learn about aquarium keeping, is to buy a larger tank. A 2-gallon tank is too small for fish. Get a bigger tank, add a filter, cycle it properly, and learn to clean it properly. The links given here will give you a good starting point for your next attempt at aquarium keeping; using this information and more that you look up yourself should make your next tank a success.