Currently, you are only dosing a small part of the fertilizers plants need. To understand what you're dosing, it's best to first understand all the ferts plants need. Then you can see what you're dosing and what you're not dosing.
There are two basic categories of ferts: Macros and Micros. Each category has different elements.
Macros:
P (phosphorus)
K (potassium)
N (nitrogen)
Micros:
several elements in trace amounts
Fe (iron)
If you want to use the Seachem line of ferts, here's how they match up:
Macros:
N (nitrogen) — Flourish Nitrogen
P (phosphorus) — Flourish Phosphorus
K (potassium) — Flourish Potassium
Micros:
several elements in trace amounts — Flourish Comprehensive
Fe (iron) — Flourish Iron
As you can see, you're only dosing the micros without the iron. If you want to dose all the ferts, you need to also dose Flourish Iron to complete the micros and then dose Flourish Phosphorus, Flourish Potassium, and Flourish Nitrogen to complete the macros.
Many people prefer to use dry ferts because they are so easy and much cheaper than liquid ferts. They are the same thing as the Seachem ferts without the water. If you go with dry ferts, here's how they match up:
Macros:
N (nitrogen) — Potassium Nitrate (KNO3)
P (phosphorus) — Potassium Sulfate (K2SO4)
K (potassium) — Mono Potassium Phosphate (KH2PO4)
Micros:
several elements in trace amounts — Plantex CSM + B
Fe (iron) —
already included
Here's one source where you can get the dry ferts. This package would last most people 1-2 years, depending on the size of your tank. For a 10g tank, these ferts would last you several years.
http://greenleafaquariums.com/aquari...rtilizers.html. Dry ferts can be put in the tank while still dry, but if you'd prefer to mix them with water first, you can. In that case, the dosing bottles are usually popular.
http://greenleafaquariums.com/aquari...nser-16oz.html
You don't have to dose ferts to your tank. I dose ferts only to some of my tanks while not dosing them to others. But if you're not happy with the plant growth you have now, even after trying root tabs, then this may be the right choice for you.