Airstone, bubble bar or bubble ball yes, all airstones. The basic ones are inexpensive but are fragile and will break down over time about 6 or 7 months and I had to replace mine. Also once it is attached to the airline tubing, don't try to twist or remove it - it will probably break. There is also these cool bubble discs that lay flat on the bottom of the tank. All require an airline and pump. I have seen more expensive bubble bars that are supposed to create very fine mist but haven't tried them yet.

I bought a bubble bar for this current tank of mine, however, the bubbles were so ridiculously small and useless in such a big place, especially since I already had another, stronger air stone

And yes, you of course need air line to lead the air into the stone. Various pumps are available as well, sometimes with several valves to be connected to air lines The whole thing is rather cheap.

I've seen some varieties, and I guess that since they exist and are sold, you could try one out

I'm looking at getting  battery operated air pumps in case the electricity should go out!
That's next on my list!

Well if you go to the pet store most air pumps will have a rating for what size tanks they are best used for and how many gallons per hour they pump.
I think though if you have a 75 gallon tank you will be looking for an air pump that turns over approximately 150 gallons per hour
All brands of air pumps will work fine - but the cheaper ones are generally louder and will not last as long.

So yeah your probably best to go have a look at the pet store! I am sure you will find something there

Yes, I read that they need lots and lots of air bubbles.
I will get a new one from the store then that does the 150gph, that's what I wasn't sure about, ty.  Didn't know if you went by the size tube or the size tank.  Will have 2 pumps with one smaller air tube and the long one with the larger pump so I can more or less make the bubbles go all the way across the back for my babies when I get them.  Patience is hard to come by right now. lol

The aquarium addict in me is going stir crazy with the tank being so bare looking. 

I did finally get the pump.  Bought the largest one they had and it said for a 30-60 gallon tank, but that was the largest so I had no other choice.  We were worried it wouldn't do the job but WOW did it do the job great!  It has two places to hook up two tubes to it so we hooked up the long wand and the other one we had that is just a bit smaller and Holy bubbles everywhere!  They run all the way across the back and the fish went crazy.  They were always swimming a little here and there but once we plugged that bad boy in it was a whole new show.  They are swimming and hunting for food constantly, they make me tired just watching it, lol. 

Btw, we haven't lost any fish yet out of the feeders we used.  Wish I had known about how to cycle without fish before we got them but they have been fun to watch during the process and the kids have named their favorite ones already.  One fish each so I guess I may have to keep some of them.  Will they go with fancy goldfish or no?  They are just goldfish feeder fish, comets I think.

Yeah I think that commons/comets really begin to look much more stunning when they are older. My comet is starting to get white markings on him and his tail is getting so long and beautiful!

You can successfully keep them with fancies. I keep one comet with a pearlscale and a fantail with no problems whatsoever. But I guess it does come down to the individual fish and how much aggression it shows to other fish and how greedy it is
The biggest problem is making sure the fancies get enough food at dinner time, as comets/commons are much faster swimmers. So I would probably say it is okay to keep them with faster swimming fancies

By the way are you planning on keeping the feeders or taking some of them back to the store? (sorry if you mentioned this somewhere else I just don't remember reading it)

@ Abbie- we were going to take all the fish back and trade them out for some other kinds of goldfish.  But 2 of them might have to stay if they survive, kids named them already and all.   The LFS owner said we can bring them back at any time or trade any fish if we don't like it or if it doesn't work well with what we have now and later on.  Nice guy!

I was thinking what you said already, that they are fast swimmers and the other goldfish I want (Ranchu for sure)  are slower I think.  But since the LFS owner said I can take any in that I don't want to keep then I could always take the feeders (only2 staying anyway) back if the new fish aren't getting enough food from being slower.  I just didn't know if they were even capable of being in the same tank and getting along. 

Was thinking maybe 7 fish altogether in the 75g tank.  This sound ok?
2 being the feeders if they can stay
5 of some fancy ones, I like the Ranchu, redcap oranda, and I would really love one of the panda ones.  Would these work together?  Any other suggestions you guys/gals have would be great!

I didn't know that about the fancies but will get them whatever they need.  Had to feed the saltwater fish pickty types of food so this should be no problem.  Guess those little feeders will ALL be going back to the pet store though since I surely want a ranchu.

Not to mention that some comets/commons may end up bullying the slower swimmers, causing you more pain when having to treat fish with various infections due to physical trauma :/
So pick varieties that can fend for themselves and "fight" for food

If you make sure the ranchus get food. Ranchus have no dorsal fin which makes them slower than orandas.
I have to make sure my fish Orbitz gets food because Titan is like some shubunkin/fantail goldfish so he is much faster.

In case you're wondering, I have ONE oranda, in a tank with... many other fish. She is the biggest, strongest and FIERCEST! xD
Really, she even tries to steal food from the pleco, and she's always first to the feeding scene, so you'll have to make sure your orandas won't be pushing the ranchu around when eating

And having it like this, there's a risk that you'd end up overfeeding one fish, just to feed the other!
I noticed I was doing that a while ago, so I'm trying to give them less, but it's pretty hard since I've got a few moors there too, and they always eat slower than everyone else There's really more to consider than just... which fish won't bully each other.

Maybe it's best to get non-dorsal fish with each other, other egg shaped fish together and streamlined fish together and not mix them Of course you can but that would be the recommendation and the easiest way especially for people newer to the world of fish keeping. Though moors have dorsal fins 

I do have extra tanks in the case of an emergency with any fish (10g and a 20g) and filters for both, along with extra pumps and air stones (pumps were too small for the 75g tank).   Need to get the tanks cleaned up though, they are being used to store all the tank stuff in atm.  All the supplies can really start to add up as I'm sure most of you know. 

Hopefully I can work it out like I said to get them in that pond.  Even if I have to keep them until they are a bit bigger.  We can still visit them also.