Nitrates, silicates, phosphates, ammonia, nitrites and get a test kit for HD
and test for metals.
And I will say it you need to rethink your method of cycling the tank... Use a SHRIMP and not the fish. You say the fish is easier? How??
Shrimp, lets see you toss it in the tank and your done!!!!
Fish, you acclimate them then feed then check water and when the levels get too high you need to do a water change to keep the fish alive. Now the cycle may last longer..
You need to slow down and read up on the cylce and Octopus also. They need a tightly sealed tank and with a overflow box I don't see that happening.
Nothing good happens fast in this hobby.....
How much lr
will you have and what size tank.. Is this the 50-55?