Simple, for a tiny little 20 l tank, you only may need a 3 liter bag, not sure who you plan on buying from, but it's still cheaper than 1.5 bags of flourite at 15$ a bag plus ship or local tax.
For a 20 gal tank, the 9 liter bag cost all of 26$. You only need one bag for 20 GAL TANK, YOU NEED TWO OF THE FLOURITE OR etc.
Shipping is less since the weight s less than for flourite or most certainly EC.
Some places may ship free on a special deal.
So yes, I have done comparisons, and have used both products.
Do not give me this poor me stuff, this hobby is a luxury thing, some folks if they are so poor as they claim, cannot afford the gravel but can afford a 300 gallon tank?
We can always do things cheaper, but what is the trade off for that, the difference between plain sand and flourite vs plain sand or flourite and ADA AS is much larger.
But then again, I've actually used all 4 substrates so I think my comparsion shopping, experience, is based on real experience rather than some speculation.
If I had a huge tank, I'd make sure I did it right.
If I could not afford things for it, then I'd go with a smaller tank.
I think I have seen 100 post over the years where one person gets this massive tank and then wants to do everything else cheap as possible.
Sand, dirt, and some shop lights. Yea, it works too.
But each thing gets you closer to having a nicer tank and the $ is worth it to some, if growing the plants well is a large concern, it behooves you to try the ADA soil.
If you have not tried it + EI, then you cannot comment.
This will maxmize the light usage(get more out of the light you use) and reduce cost over time and give folks more wiggle room in their routines.
Maybe saving a few $ is not worth that, but over time it sure is........
The cost for doing a large 300 gal tank would run about 500-700$ with the ADA soil.
Given the constraints, the Soil master or good old 2-3mm sand will work.
I'd not spend the $$$ for flourite for such a large tank, 15 bags will not be enough either.
15-20 9 liter bags would be about right for the 300 gal, these are2x the volume per bag of EC or flourite.
You also do not have to rinse ADA AS, except for EC, the others you do.
ADA AS is also the only thing that will not scratch the glass if you get it caught in between the scrub pad like always happens over time.