By the sounds of your last post ... it seems like your realizing the demands of this hobby. Yes it can seem overwhelming at first ... but once your tank is established ... it's more or less downhill as long as you keep up with maintenance.
To answer your question .. an airstone is a porous rock connected to an hose and air pump. IMO
tank .. planted or not ...should have one ... it increases surface area that helps promote gas exchange (O2
etc out) by agitating the surface.
If possible start by rehoming some of your fish ... the tank is overcrowded which means a bunch of ammonia is being put into the water. With clown loaches a 55gal should be the minimum and then only a couple. As you read ... common pleco's can get HUGE ... a bristlenose pleco may be more reasonable for your size tank.
Without knowing your water parameters ... I'll just assume your tank is not cycled yet. Below is a link on cycling ... the key will be to test the water daily and be prepared to do 50% PWC
's. If you can I would highly suggest you buy a bottle of Seachem Prime dechlorinator ... it helps detoxify ammonia and nitrites for up to 24+hrs giving the fish some breathing room till the next PWC
I just learned about cycling but I already have fish. What now?!
What is the name of the filter you are using ... it could be you have inadequate filtration for your stock which contributes to tank issues. You may also have to upgrade to a more powerful filter.
It sounds like you have a lot of ideas / plans for your tank and this site is a great place to go for help.
75g Planted Barbs Denison, BlackRuby, Tiger, Albino Tiger, Green Tiger, Cherry, Gold, Checkered, Odessa.
NonBarbs Cardinal, Neon, RummyNose, Bloodfin Tetras, Z. Danios. 1RTS. Amano, Bamboo, Ghost & RCS. 20g Long Shrimp Tank RCS, Tiger, Amano.