[advice Requested] Re-building 3.5g Tank Project. Very Text Heavy!

So I've had a 3.5 gallon Blau Cubic tank set up for a couple of years now and I've had Red Cherry Shrimp on it since the beginnig. It was rather heavily planted, with a piece of driftwood completely covered in Java moss. The shrimp population grew quite big and I had a lot of Physa snails too, which came as stowaways on the store-bought plants. Due to study and work I started slacking on maintenance and let the plants take control, but still made weekly or bi-weekly water changes.

Skip to last month after a bunch of shrimp started dieing and I decided to turn the tank around, give it a good cleaning and start with something different. I started taking most of the overgrown and even rotting plants out, as well as all the Java moss (which had started to root on the walls). Scrubbed most of the algae from the walls and syphoned the substrate. Mind you, I hadn't syphoned the tank in over a year. At this point, I wasn't too worried about the shrimps and I'm happy to say that all 5 remaining before the teardown survived just fine! Anyway, I want to take it more seriously so I've upgraded from a 9W PL tube to a LED lamp and also got a testing kit. This is my current setup, I'll try to post as many technical details as possible:

- Blau Cubic 3.5g tank
- Blau FM-60 hang-on filter (16 gallon/hour filtration, just stock sponges, no additional filter media)
- Blau Nano LED light 2.0 (light output 11.000 Lux at 25 cm, two separate dimming channels, 19 LED 6500ºK White + 2 Red)
- No heater (yet, water is on the cold limit)
- Azoo Carbon Plus liquid CO2 supplement (see routine below)
- Organic substrate (maybe akadama? I can't remember...)

Population:
- 5 adult RCS
- Bunch of Physa snails (no plague yet, but in that case I could control it easily)
- Had 2 Otocinclus Affinis, but after a couple of weeks both died suddenly

Plants:
- Small "bushes" of HC 'Cuba' (planted recently, carpeting in progress)
- Two small Cryptocoryne Costata (I think? It's the closest one I can find on the Net)

Routine:
- 8 hour photoperiod, both channels on the light set to about 70-75% on both channels (channel 1 is 14 white LED and channel 2 is 5 white and 2 red)
- 7-8 drops of liquid CO2 daily or 13 drops after weekly water change, as indicated on the instructions.
- Weekly 30% water change. Refilled with regular tap water, no conditioner used.
- Feeding shrimps twice a week with shrimp wafers.

Parameters (tested today for the first time ever!):
- pH: between 7 and 8
- Ammonia: 0ppm
- Nitrite: 0.1ppm
- Nitrate: 2.5ppm
- GH: 10º dH


My concerns and doubts so far are basically as follow:
1. Are the parameters OK? From my understanding, I should try to lower the Nitrite to 0ppm and maybe not use tap water to reduce the General Hardness too.
2. Is the photoperiod and CO2 addition addecuate for the growth of th HC Cuba? So far I haven't noticed an increase on algae growth but the walls seem to be covered with a thin layer of biofilm since last week.
3. Should I upgrade the filtering media? Maybe add ceramic filter rings?
4. Once the plants grow and the parametes are under control, would it be possible to have a Betta along with the 5 RCS (yes, I'm aware the Betta might see them as food) and maybe a Nerite to deal with algae?

Sorry about the text wall, but if I wanted to provide as many details as possible! Anyway, thanks for reading and taking your time to answer!! Feel free to make suggestions too! Here are some pics of the tank (it looks quite bare now and the fake rocks and tubes are only there to weigh the root down).

 

Wait. 30% water change with no conditioner? Unless you live on a heavy metal free well, you need conditioner.

 

Wait. 30% water change with no conditioner? Unless you live on a heavy metal free well, you need conditioner.

Noted! The water in my town is regarded as being quite good so I've never considered adding conditioner. I want to start doing things the proper way now, so I'll start adding it! Any in particular?

 

Seachem prime is usually the best water conditioner

 

Seachem prime is usually the best water conditioner

Great, thanks! I was just thinking today about removing most of the Physa snails (found out that they're called Bladder Snails too) and introducing a Nerite instead to deal with algae growth. Since the HC Cuba has rather high light requirements, I've been noticing more algae on the corners of the walls and lately, a thin layer of biofilm too. Would a Nerite help keep the tank clean? I've read the produce a lot of excrements so I'm not sure if I'd be overstocking the tank if I decide to put a Betta in it in the future.

 

I have a netrite snail in my five gallon and he's doing a nice job. Everyone always says the best algae eater is yourself though lol.

And I think you could totally get away with the betta too, but he might try to eat your shrimp obviously so beware.

 

Its easily large enough for a betta and nerite. Of course the shrimp may get eaten but its probably not likely if you get a young betta.