PH drop, CO2 to blame? Effecting ammonia?

[Chikpeas]

Hi!

So I did a fishless cycle with my 7.1 gallon, used fresh live sand, dry rock- turbo 900.

Starting params after tested cycle:
dKH: 9.5
PH: 8.1
Ammonia: 0 ppm
Salinity: 34/35
Nitrates: 5
Nitrites: 0.05/0

I’d feed my tank to .2 ammonia, monitor it, watch it drop in 24 hours.

Added my first fish with cuc, small ammonia spike- dropped within 24 hours. Started to notice a slight cat urine smell but it went away when the ammonia dropped to 0.

Accidentally covered my tank, had a ph drop, nitrates Zerod.
Uncovered tank and raised oxygen, pH returned to 8, alk raised to 11.5-12

Second fish? A tiny goby.
Came home today and smelled strong cat urine from my tank.

Ran to the tests.
Ph: Dropped to 7.6
Ammonia spiked to .2 ppm
Nitrate: nothing.
Nitrites: 0.2

I thought I had plenty of surface tension, there’s no algae, my fish are active, hermits are active, all but my cerith snail keeps trying to escape.

My next thought is… could it be CO2 buildup? It’s not our house itself, our air unit pulls air in from the outside. My room however…. I always kept my door shut to maintain the temp for my dart frogs. My basement is almost always 60 degrees f. There’s not much air flow in here. I don’t even think there’s a vent in here. I’ve started to leave my door open a few hours in the day, but I’m thinking that not enough now.

Do I need a fan to move things around?
Would low oxygen Kill beneficial bacteria or effect my tank someway like that causing a second cycle?
Annnnd would a water change atm help add oxygen to the tank and reduce ammonia?

Any help would be appreciated ),:

 

[Randy Holmes-Farley]

The pH is not a concern right now.
Ammonia was dosed to 0.2 ppm, not 2 ppm?

 

[Chikpeas]

The pH is not a concern right now.
Ammonia was dosed to 0.2 ppm, not 2 ppm?

whoops, sorry typo
2 ppm not 0.2

Ammonia dropped before bed last night and the smell reduced quite a bit.

This morning it’s back to a solid .2

 

[Chikpeas]

The pH is not a concern right now.
Ammonia was dosed to 0.2 ppm, not 2 ppm?

My wrasse is displaying odd behavior by swimming the outline of the tank and blindly bumping into things. I don’t see any heavy breathing, just like he woke up very confused.

My goby is fine, but I work 9 hours today and I’m very late already. Idk what is going on. I turned on the bubbler before I left in hopes that it might help the wrasse until I can get home.