Actually, when it comes to fertilzation in a fully aquatic environment, there are only 5 option, hardly a lot. All natural, from waste byproduct from any fauna in the tank, which is rarely ever enough unless you keep goldfish, which would be counterproductive because they will eat any flora in the tank. Then you have liquid fertilizers. Next are dry fertilizers. Potassium nitrate being the most important. Next are root tabs and lastly, dirt.

I always recommend dirt to any beginner as far as plants go because it has numerous advantages. One being is you have plenty of ferts available to the root feeders like crypts and swords as wells as some stem plants that benefits from soil fertilization such as wisteria, water sprite and a few of the ludwigia species. This benefit lasts for YEARS, not a monthly basis, like root tabs. Most beginners eventually have their plants go the wayside because they forget they have to buy root tabs monthly. In the decade or so I have kept aquatic plants, I have seen it time and time again. Soil also keeps your water parameters stable. And, if your water supply is naturally hard, the peat and humus in the soil help naturally buffer the water to a more soft, acidic water, which benefits the plants.

I have gone every single route there is with aquatic plants, from high lighting, dry ferts and massive amounts of pressurized co2 to low light, dirt setups. By far, dirt were the lowest maintenance. Set it an forget it.

Now, I am not trying to convince you to go dirt, because I really don't give a flying one. But flooding the forums with threads when you get advice from other threads is just basically, putting one member against another. Not your intention, I am sure, but it is the reality of the situation. I myself, will have no more of it. As far as advice, I am done with you. But I at least wanted to validate WHY I have dirt as a suggestion. Good luck with your tank and your frogs.