Hello,
The correct answer lies within you. It depends entirely on why/how you are using peat , as well as why/how you are using Purigen. Each has a function, but if we misunderstand the functions then it can be easy for the effects of one to be canceled by the effects of the other.
The only good reason you should be using peat for is to break it up and spread it across and throughout the substrate when setting up a new tank. The peat disintegrates and becomes a source of carbohydrates for the sediment bacteria. It's not really useful used in other ways. It's decay process results in acidification of the sediment, which is advantageous for some chemical processes in the sediment, however, ultimately, detritus and organic waste settles into the sediment and have the same acidic effect, but that happens more slowly. In any case, the use of peat and it's effects PALE in comparison to the power of The Dark Side of The Force. That being malnutrition and carbon starvation.
The good reason for Purigen is to remove dissolved organic waste and debris such as produced by decaying peat. The type of dissolved waste Purigen is good at adsorbing are the particles which by coincidence are less transparent. These forms are most responsible for a hazy or cloudy water. So the result is that the water becomes clearer because these dissolves particles are removed from circulation, being trapped on the surface of the Purigen. If you can't afford Purigen, then you can achieve the same results by simply making more frequent and large water changes. That will have the added benefit of removing toxic dissolved components that Purigen cannot remove.
So if you pay attention to the fundamentals you will have no need for either, or you can use them advantageously.
Cheers,
None of this is related to plants at present, although it is technically a low tech aquarium with a few anubias and java ferns at the moment, but am planning to increase this.
