Hi,
If I have valuable space in my filter for media then peat granules would not be on the top of my list. I would be more likely to use something like zeolite or purigen which
remove toxic components like ammonia from the tank. I would resist the temptation to add things to the tank except for the important items such as nutrients and CO2.
The marketing hype associated with peat granules is based on someones dreamy personal vision of what Amazonia
ought to be. Peat does help to soften the water and to acidify it. Before RO units became widespread, mass quantities of peat was used to soften and acidify water and was mostly used by Discus and dwarf cichlid keepers/breeders. This necessitated the use of large water holding vessels and was generally a tedious procedure.
But lets get real for a moment. Peat is essentially rotted vegetation so there is no way that it will inhibit bacteria. In fact, why would you even
want to inhibit bacteria?
Bacteria do all the work for you in your aquarium. They reduce toxic ammonia, the end product being nitrate which feed your plants, so why should you inhibit bacterial growth? When a tank is being started up it's a good idea to put a layer of peat at the base of the substrate in order to provide valuable carbon for the young bacteria colony which then later purifies the substrate and facilitates nutrient transfer from the substrate to the roots of plants. So these claims of bacterial inhibition are absurd on so many different levels, that these claims could only have been conjured up by some video game marketing department.
For the purposes of plants the actual value of humic acids is yet to be determined. Humic acids probably have more value to fish health. Trace elements are best supplied via inorganic salts that we dose. Certainly, algae are not going to be foiled by humic acids or anything else that peat granules supply. Algae have seen it all, and if you fail to nourish your plants adequately algae will scoff at your peat granules and will roll across your tank like so many Panzer divisions of the Wehrmarkt.
Lastly, the vast majority of plants will do fine in high KH/GH environment so there is no need to attempt to modify your water to be soft and acidic. Besides, if you are adding CO2 to the tank then this will acidify the water anyway. Plants are largely pH insensitive.
Make you life and your hobby easier by ignoring the conditions of Amazonia and putting something of greater value in your filter. The only circumstance that would validate the use of soft acidic water is if you are attempting to breed or keep soft water fish, or the half dozen or so softwater plants. If that is the case then it's better to simply use an RO unit to produce soft water.
Hope this clarifies.
Cheers,