Personally for someone getting used to dosing and planted tanks I would follow the EI method. Although it can be a PITA water change wise it will force you to get the CO2 right but be much more forgiving on the nutrient side.
Not part of EI but I would first get your lights on timer for an 8 hour photoperiod. You may move up to 10 later but this will limit algae's chances whilst provding the plants plenty of time for their photosynthesis.
Basically EI is this.
CO2 - Again put the solenoid on a timer and set it to start 2 hours before the photoperiod starts and stop 2 hours before the photoperiod ends. Set it up so your DC is green within the first hour of the photoperiod (with the timelag of the DC this would mean CO2 is at 30ppm(ish) when lights are on. I don't need to explain that you need to be a little careful if this means you are upping from your current setup.
Next are the ferts. Macros (NPK) and micros (Trace Elements)
You will have 3 bottles - One for the Potassium Nitrate mix, one for the Potassium Phosphate mix and one for the trace.
Mix them as follows:
Solution 1 (KN) Add 40g of Potassium Nitrate to 500ml of DI water
Solution 2 (KP) Add 15g of Potassium Phosphate to 500ml of DI water
Solution 3 (Trace) Add 15g Trace Elements to 250ml of DI water. You can use the hydrochloric acid in this one if you want but I don't. It is mainly to some fungus/mould. If worried just make up a smaller amount i.e. 6g to 100ml etc.
Now you have your 3 solutions your weekly schedule would be based on a 40-60G tank.
Day 1 - 50% water change then add 30ml of solution 1, 18ml of solution 2
Day 2 - 10ml of solution 3
Day 3 - 30ml of solution 1, 18ml of solution 2
Day 4 - 10ml of solution 3
Day 5 - 30ml of solution 1, 18ml of solution 2
Day 6 - 10ml of solution 3
Day 7 - Do nothing - rest day
The theory here is that you are adding more than the plants are likely to need over days 1-6. The 7th day will take up a bit of the left overs and then the 50% water change will 'reset' the levels.
So you need to buy several things really. More expense but these things will last absolute eons. lol
KNO3 (Potassium Nitrate) powder
KH2PO4 (Potassium Phosphate) powder
Chelated Trace element powder
Cheap digital scales off ebay
DI water from Halfords or Wilkos etc.
I would buy 500g of each powder from Aquaessentials. There is quite a difference between how fine/soluble the powders are from several sources and I have found AquaEssentials much better than some others. 500g of each will last over year in the case of Potassium Nitrate and a couple of years for the other 2. Links below:
http/www.aquaessentials.co.uk/index.php?...products_id=474
http/www.aquaessentials.co.uk/index.php?...products_id=475
http/www.aquaessentials.co.uk/index.php?...products_id=753
They may look expensive at first glance but when you weigh the cost up against buying a decent off the shelf fert over the time period these will last then you are looking at a fraction of the cost in comparison. Fert companies dosing suggestions are tiny compared to what any experienced user will use.
Then I would buy a set of 'herb' scales like these:
http/cgi.ebay.co.uk/Pocket-Digital-Scale...id=p3913.c0.m22
To measure the mls I would suggest either using 10ml (1ml increment) syringes or medicine measuring cup etc.
There you have it. Basic EI for a beginner. You are in a much better position than most people who start on EI because you already have the knowledge of pressurised CO2 and flow is in hand. Most scrimp, start, beg for help and then have to catch up or give up once they realise they need to spend a lot more!!!
Good Luck
AC