Goldfish stocking help

[SharpieItBlack]

I know goldfish are wasteful and poo a lot and so I do water changes once a week, and clean build up on decor once a month. So far after upgrading to a 30 gallon, my water conditions have improved greatly. Just have one goldfish, about 4 inches long. I want to add another goldfish of his same type.
But I've heard 20 gallons for the first fish and 10 for each after. Based on that I could, I just am really worried about water conditions and the health of the fish. I don't want to run into the same problems as with my old tank. I've also hear, 30 for the first and 20 for each after. That just seems a bit big.

Any opinions? The tank is lightly planted, however next water change, I'm adding 5 more pounds of gravel and rearranging the decor (my fish likes to explore new things so rearranging keeps him entertained).

To clarify I have now...
30 gallon tank
One calico telescope eyed goldfish
All artificial plants and decor
Water conditions average, though after each week it basically just gives readings saying I need to change the water.
I use a water conditioner and ammonia detoxifier, both for Amquel.
I feed homemade gel food and occasional veggies like peas.

 

[GNarnian]

What type of filtration are you using?

 

[SharpieItBlack]

What type of filtration are you using?

Whoops I meant to post that haha. I am running a newer filter said to be used for up to a 35 gallon tank, and an older 10 gallon filter.
I plan on replacing the 10 gallon one with a new 20 gallon filter, I'll be buying it next time I'm out and about this weekend.

 

[Sharpchick]

A cycled 30 gallon tank with adequate filtration should be able to house two fancy goldfish.

More questions...

What are "average" water conditions? Are you actually testing your water chemistry?
You said the tank was lightly planted, but then you said all artificial plants. Does that mean you have a few artificial plants?
Have you made sure that all plants and decor are safe for the eyes of telescopes?

And an observation...if you add a fish, I'd add another of the delicate fancies, as opposed to a ryukin or oranda.

 

[GNarnian]

And an observation...if you add a fish, I'd add another of the delicate fancies, as opposed to a ryukin or oranda.

+1 to that

otherwise you'd end up with Jack: The no-eyed goldfish. :-(

Which happened to a black moore of mine, but he doesn't seem to care, and he's been like that for a looong time

 

[SharpieItBlack]

A cycled 30 gallon tank with adequate filtration should be able to house two fancy goldfish.

More questions...

What are "average" water conditions? Are you actually testing your water chemistry?
You said the tank was lightly planted, but then you said all artificial plants. Does that mean you have a few artificial plants?
Have you made sure that all plants and decor are safe for the eyes of telescopes?

And an observation...if you add a fish, I'd add another of the delicate fancies, as opposed to a ryukin or oranda.

I think I said I'd get the same exact type of goldfish in the first post, not sure. But average I mean like ideal conditions for ph, ammonia, and the nitrItes and nitrates. As in everything is as it should be. I test my water twice after each water change. And yes I have few artificial plants. And they are safe. When I upgraded and bought more decorations, I ran my finger along it and if it seemed even a little sharp I didn't get it. I have a crashed airplane and rocks in there, everything else are silk plants.
Which is also important for any fish I think you don't want them to tear the fins on sharp decor!

Hopefully that helps