From what I've read the blue light spectrum is not the best for plants, you should go with a full spectrum or pink spectrum bulb.
And as far as filtration is concerned. I would suggest going with one of the nano canister filters. They will be $15-20 more expensive than your HOB but it will be worth it for many reasons. HOB filters aren't very attractive, plus if there is even a minor power outage they will stop and not start back up until you add water to it. I've had it happen to two of my tanks the lack of surface agitation caused a CO2 buildup and killed almost all my shrimp. On the other tank I ended up getting green water.
There are many different canisters you can get that will work.
Also with putting the CO2 into your HOB filter you'll have a lot of off-gassing when it splashes on the water surface.
With the lace rock you plan on adding it will add dissolved minerals, at least that was my experience with it. Which is great for a shrimp tank.
And with the size of your tank, you should pretty much just go full RO water since even with 50% water changes that is only 2gallons.
With your light you'll be able to grow just about any plant, it is actually a bit too bright and figuring out the right photo period will be very difficult. You may want to suspend it a few inches over your tank. And with any tank with high light you'll need fertilizer.
As far as fertilizers go I started with Seachem Flourish which contains all your micro nutrients. Then Flourish Phosphorus. Then I bought API Green Leaf which contains your Iron and Potassium. Which for the most part can be picked up at your LFS. As long as you stick with a single 4g this should last a full year maybe longer. However you'll find that this is addictive and you'll get more tanks. Once that happens you should buy dry fertilizers and dosing bottles to make your own versions of those name brand ferts.
I have quite a bit of experience with reefs, but it's been a while for that. I kept FW fish as a kid, but it's been even longer.
Requesting help three ways:
1) Please let me know of any terrible flaws in my plans.
2) Please recommend stocking plan for plants. I really have idea what to start with. The LFS has quite a selection, so I should be able to find most things. Nutrient recommendations here would help too.
3) Please recommend a stocking list for fish/shrimp. I was thinking of a couple of shrimp and some schooling nano sized fish.
Anyway, here is what I have going equipment wise:
Finnex 4 gallon rimless tank with 26 W blue/white CF bulb
Aquaclear 20 HOB (with bio, carbon and sponge media)
Hydor 7.5 W heater (will place in HOB filter, not sure I need in summer)
Digital remote thermometer
2-3 inch Flourite base
1-2 inch aquarium sand layer
small driftwood and small texas holey rock pieces
Half RO/DI and half tap water (fairly hard water)
SeaChem Prime added to water
DIY yeast/sugar CO2 setup inserted into HOB intake
Ammonia and multi (nitrate, nitrite, co2, etc) test sticks
My plan of action:
I plan to first rinse the substrates and rock and driftwood well and then place it in the tank. I will then fill it and let sit for a week or so.
Then I will go get some plants and get them going and let that sit for another two weeks. I'll start the CO2 at this stage.
Then I will introduce the first batch of either fish or shrimp and monitor for a few weeks of a month.
Then I will add the second batch of shrimp or fish, monitor and maintain- changing a gallon of water every week.