This is my first walstad tank. I want to put a betta fish in it. I set it up February 22nd. So it’s been 2 weeks exactly. I seeded the sponge from another tank. As of today the water parameters using the API  master kit, are as followed 

Nitrate- 10

Ammonia- 0

Nitrite- 0

KH- 4 

GH- 8/9

ph- 7.4 on high range (7.6 on regular) 

\^These parameters are almost exactly what it was like after week 1 test

I want to add a big center piece of wood, a hammock and some rocks lining the grass in the middle. 

\- What type of wood have you found best/where did you buy it from?

\-From your betta experience are these parameters fine?

\-Where do you buy your leaf rubbish for tannins?

\-Anything else should I add for a betta? 

\-Do you guys let your tannins release in the water before you add your betta?

\-Is a sponge filter adequate for a betta? I know they prefer low flow tanks 

\-I am using a plant grow light right now, would that be an adequate light for a betta fish? (it has automatic timer but only one level of brightness) It’s a two head light so I can always move one away if it’s too bright 

This is a 15 gallon tank. Yes I plan to get a lid, and I have a heater that I can regulate in a quarantine tank right now, it will be added to this tank instead of the pre set heater after quarantine is done. And yes I will be topping off the water and vacuuming out the debris floating around

Okay people, I need advice. Information in caption :)