First post here for me...
I've been a strong believer in both products and still today prefer either one of them to any other brand. I initially started using TMG as a trace mix, then switched to Flourish + TMG, then to Flourish + CSM+B. I think the Flourish + TMG mix was the best solution, I plan to go back to that once I finish my exaggerated supply of CSM.
The major differences I have found between these two products are:
- Flourish is by far the most complete trace mix on the market
- Flourish is more concentrated which makes it the cheaper long term solution
- TMG contains 73 times the amount of potassium in relation to the amount of iron contained in both
- TMG contains no other macros or vitamins
- Flourish contains a lot more FE
TMG was the better solution when I lived in Italy, many European water sources have a higher phosphate and mineral content than US sources, at least the ones I have had the opportunity to use. I think this is possibly one of the reasons why certain elements are omitted from TMG. Flourish on the other hand contains a little of everything, even the new Kent Botanica line requires 3 different products to come close to the contents of Flourish.
In the end, I can't say one is better than the other, they are just different. For a basic low-medium light tank Flourish is probably the best product to start with, specially if it's going to be the only product you add to the tank. In a high nutrient tank we are used to dosing macros so the fact that TMG doesn't contain P or N is probably a good thing, or at the very least, we couldn't care less. Its' high levels of K however could possibly throw off your values if you use KNO3 as a nitrogen source. Flourish on the other hand has a lot of FE in relation to the other elements. If like many of us, you use FE levels as an indicator for dosing traces, a TMG user targeting a certain FE level will end up with a lot of K and a good amount of other trace elements. A Flourish user targeting the same FE level would instead end up with a smaller concentration of other trace elements, however a broader range of them.
In conclusion, taking contents and recommended doses, Tropica seems to recommend a higher level of traces than Seachem. Both recommend the same amount of FE however.
It's a little easier to see these differences in the following tables:
This is a comparison of what's in each of these products.
This is a more useful comparison. The values have been standardized based on FE contents to provide a baseline regardless of concentration. At the bottom is a small table indicating FE levels based on recommended doses.
So for me mixing the two gave me the best results.