Freshwater aquatic snails would be the best choice for a tank that small.
6 foot
I do not know of any Algae eaters that can live in cold water . Goldfish are cold water fish. So unless you can find some species of cold water algae eater the answer is no they can not be kept together successfully.
Easy. Fill the 7gal pail to the full mark (7 Gallons) with water. Then pour, from the 7 gallon pail, water into each of the 3 gallon pail up to the full mark. The remaining water left in the 7 gallon is 1 gallon. Pour this gallon into the aquarium. Fill the 7 gallon pail with water, again to the full mark, and then add to the aquarium. 1 Gallon + 7 Gallons = 8 Gallons.
Plecos work well in ponds and cold water aquariums.
right around 400#.... water is about 8# per gallon.
algae tends to grow faster in clean water. so it depends if the aquarium is clean or the lake.depends on what lake.
There are many different aquarium animals that will clean algae off the walls of your aquarium. I will name a few: Cories, Plecostomus (AKA, Pleco) and more. There are some algae eaters that are not fish. Mystery snails, freshwater snails, and other water snails eat algae. Ghost shrimp are small and are very easy to take care of. They clean the decorations in your fish tank and eat any uneaten, leftover food.
The general rule for stocking a fish tank is 1 inch of fish per gallon of aquarium water.
Water snails eat algae, bacteria and other small plants that live in water,
It doesnt need that much water, even a small plastic cup would work.
24 hours and do a water change
You should only have 1 fish per gallon of water in a fish tank. I wouldn't put more than 2 or 3 Neon Tetras in a 4 gallon aquarium with 1 Betta.