You can safely use ammonia, just make sure to rinse it well. Fish create ammonia as a waste product. If the tank is cycled (and yours is if you’re moving the filters/media/gravel/plants) it’ll handle any ammonia that’s still in there. If the new tank isn’t cycled, you’ll need the ammonia to cycle it before you add the fish, if you’re doing a fishless cycle.
Ace Hardware is one of the few places you can find Pure Ammonia with no surfactants.
So, no Lime away? How do you get rid of lime deposits? Can I use Lime away on the outside? Do you think letting it stand with tap water for 24 hours is long enough to make sure is doesn’t leak? I thought I would put it on the floor on newspaper and a towel.
Do I really need to run a fishless cycle if I am just transferring their water immediately from the old take to the new tank, and I have the same substrate, decorations, plants, and filter media? The fishless cycle seems counter-productive, as it will cause the old bacteria to die off. I am goinf for 20 gal to 30, probably, so the new water with be 25% of the water. That’s no different from a 5 gal change in the 20 gal tank.
I wouldn’t use random chemicals like CLR or Limeaway, I really don’t know what’s in them. Ammonia is the only one I know is safe to clean an empty tank with. Just do a really good job rinsing it afterwards. Even better if you can do it outside (or in a basement by a floor drain) so you can flip it on a side and hose it out afterwards.
As for the outside of the tank, you can use anything there.
When I started up my tanks, that had previously been desert type lizard tanks (with heat lights in them), I filled them about half way with water and let them sit for about a day to make sure the caulk was still holding. I think that’s safe. I did it in my basement. 24 hours was enough time to let the concrete dry from any water I had spilled while I filled it and let any leaks appear (and none did). And since it was right next to a floor drain, I really wasn’t concerned, even with a catastrophic failure when I wasn’t around.
No, you don’t need to cycle the tank because you’re moving the ‘stuff’. The beneficial bacteria live on the substrate, the decorations and the filter media. Moving the water isn’t the big of a deal. I’d move at least half of it just so the fish aren’t shocked by getting all new water, it’ll be like a partial water change. But as long as you move the a good chunk of ‘stuff’ from the old tank, it’ll already be cycled.
Just to be clear, it’s not the water that’s important, it’s the items in the tank, the majority of the bacteria that keep your tank healthy live on surfaces, not swimming around in the water.
Thinking about it, the one thing I’d be concerned about is the amount of crap you’re going to kick up when you move the substrate.
I’m not sure what the answer is there. It might be worth replacing it, or at least half of it and only moving half. They even say when you clean it, you should try not to kick it up too much because there’s a different kind of bacteria (anaerobic IIRC) that gets way down to the bottom. Even if I’m wrong about that, I think it’s just going to be filthy if the tank’s been operating for more than a year or so. You’ll probably be able to tell when you start moving it.
If it is, it might be easier to pull it out, clean it and then put it back in.
If you clean it with tap water, you’ll lose some of the BB and you’ll either have to keep an eye on your levels or just count on some extra PWCs as you might go through a mini cycle. If you want to avoid that, clean it with old tank water.
…Or I’m just over thinking how dirty it’s going to be.
ETA, poke around here for all the help you could possibly need with your aquarium. It’s not quite as active as this board and I try to keep an eye on post counts when I’m taking advice, but it’s a good resource. If you have some time before you make the move, you might want to ask them as well, but since it’s where I learned just about everything I know about aquariums, it might be the same answers.
My plan was to use a net to remove the top half of the substrate as carefully as possible, then move the bottom to the tank, then take the top half, and mix it with the new substrate I’ll need for the bigger tank, and put that on top. The I will put in the plants. I have a huge Anubias, and four smaller plants. Then I will add the decorations, plus some new ones, then start putting in the water that the fish are not in, and then the new water and the heaters, and then the old filter, if it’s deep enough.
Once this water gets to the same temperature as the water in the holding tank, I will net the fish into it, and add the rest of their water.
I’m not going to add any new plants, because I’m always having to thin my Anubias, and I’m hoping to let it grow a little bigger and fuller.
I use root tabs. I’ll be putting new ones in.
I have always heard that anubias roots will rot if they are in the substrate. Mine are tied or glued to rock.
I’ve cleaned lime deposits with vinegar. I use it to clean the containers that I grow brine shrimp in. Of course I rinse thoroughly.
Using some of the old water will keep the dissolved solids and pH that the fish are accustomed to.
My Anubias is mostly above the substrate. It is pretty big, and the ends of the roots are in the substrate, and there is a root pellet there. It’s small gravel. Because it’s a big plant, it stays put. The leaves occasionally rot, and have to be removed. Whenever I change the water, I check it for leaves with rot and remove them. The fish love to swim in and around the leaves.
My Wife’s panda garra like to sit on the leaves. 
The loach and the guppies like to do that too. The cories did that when they were smaller.
I was surprised to find out that guppies sleep at the bottom of the tank. The first time I saw it, it freaked me out.
Well, I’ve got a couple of wrenches in the tank. The vacuum booster on my brakes went out, so I have to put off purchasing my equipment for a week.
Also, I had a bacterial bloom in the tank.
The bloom is my fault, I think. I used tap water (with dechlorinator) to change it (pinching pennies) instead of bottled water. Usually, I use three gallons of spring water, and one of distilled (yes, I know not to use distilled in general, but the spring water has a high pH, and is hard, and the distilled corrects for that; since I put freshwater salt in the aquarium at each change, and I have live plants, a little distilled to correct the pH and hardness has so far worked really well).
So, now I’m waiting for the water to clear. I bought two gallons of the good stuff, and put a little Seachem stabilizer in it. Now I just have to wait. The fish are fine, and the parameters are fine-- no nitrates or nitrites, low ammonia.
Anyone have any advice on bacterial blooms?
Also, I found someone who is selling a 30gal long tank on Craigslist, with a hood with fluorescent lights for $5. The tank has a crack, but he says it doesn’t leak. He won’t sell just the light. I am considering buying it from him, and then just tossing the tank, because brand new tanks with no lid or light can be gotten pretty cheaply, and lids with plant lights are expensive. Any opinions? Naturally, I will test the light. If he doesn’t have a lamp in it, I will insist on getting one and checking it, and I will test it with a multimeter, inspect the cord for cracks, etc, although I’m pretty good at things like replacing cords.