Need To Buy A New Tank - Need Recommendations

Yeah, no way I'd put it in the tank in the substrate as we went through hell to FIND a good black substrate. For the purpose of it being black. 

I ordered a little sample bag for a couple of pounds and will see what shows up.

It would probably be easier to find a lump of dolomite and use that as a rock in the tank. For example dolomite (the examples that are just dolomite, nothing else)


Yes, things do seem to be moving at last.

Probably all three.
The nasty pad would have contained bacteria
Extra time for those bacteria to multiply (they can double thir numbers in 24 to 36 hours)
The water change would have removed some ammonia & nitrite, but also added some KH. Not much, admittedly but it would have helped. The filter bacteria also need inorganic carbon to grow, and inorganic carbon is just carbonate and bicarbonate.

If sodium carbonate is the only ingredient, you can use it during cycling. But the sodium will make it unlike the water your fish come from (cories and any other soft water fish) so I wouldn't use it once you have fish.

The common name for sodium carbonate is washing soda 

Washing soda is also good to use on drains 

Good to know!

Oh, big surprise for me here this morning. Was sitting next to the tank, drinking my coffee, when I noticed something moving in there under its own power. It seems there is an incredibly tiny cory in there - must have been an egg in the filter, or a larvae in the filter, when I added the janky old filter to the tank and then pulled the  filter medium out in the water!  So, something is alive in there besides the plants!  "Rambo" seems to be doing fine, rooting in the fine black sand up under the plants.

I did a 1/3 tank water change, as I'd added enough "Up" yesterday to get the tank to register a change in Ph on the test scale. This morning it was back down to 6.0, the ammonia seems a bit lower (hard to tell) but not yet zero, and there is definitely more nitrate in the tank. The nitrite remains, of course, purple and I can't tell the difference between the three of the purple colors on the card.    Since Rambo is in there now I'll be changing a bit of the water every day until this weekend, and then will chance a couple more slightly older cory babies in it. (With Amquel in the water to neutralize the ammonia, etc.)

Ok, now THAT was weird! 

I had the big tank running since May. I cleaned the filter out in June. In July I only took the top sponge of the filter out to clean (there are two), and added a bit of alkaline gravel.  In early August I cleaned the top sponge again (so as to leave the bottom sponge with the bacteria).  Yesterday I decided to give the filter a good clean, so I turned it off, drained the water and took it to the kitchen sink. I pulled both (very gunky) sponges out and kept them in a bowl of tank water. I then turned the housing over under running tap water and shook it. Out popped a good-sized albino cory into the sink strainer. I thought it was dead, then thought again - how would a cory that big get into the filter? I looked closely and saw a gill move! Holy Moley, he was alive. 

So I got him into a net and back into the big tank - where he went straight to the bottom and began to root in the sand.  My daughter agreed that was weird - he must have been sucked into the filter as either a fry or an egg right after the tank had cycled, and had been living in that tiny space for at least a month (probably closer to two, given his size).

So I thought nothing more of it. I dumped the gravel out into a bowl and was washing it and, yes, there, in the gravel was ANOTHER cory, about half his size. Same drill - emergency transfer to a net and into the big tank. Straight to the bottom and began to feed. Pwew!

So, back to the gravel, which I had been sloshing around in running tap water for a good five minutes. Noooo, was that a flash of pink? Yes, it was. A tiny cory had been sloshed around in the gravel, in running cold tap water. Net. Tank. Bottom. Feeding.

So, today, the filter is re-assembled, Tetra Safe-start added to it, and back in the tank. The three "new" corys are doing well. I am, once again, up to my eyeballs in albino corys - we had planned to keep six, gave away what we thought were the rest. Between eggs that were well-hidden in the tank and these three guys who lived in that tiny one-inch by one-inch space in with the filter and heater, we now have fifteen again!

Those are some darned sturdy little fish!!! 

Anybody want any albino corys?

Wow, that's some hardy corys. 
I wouldn't have thought they'd live in a filter, or survive being run under the tap. 
Amazing.

Wow, what a good and impressive story, with a nice outcome on each occasion. 

Your tank looks great