Which substrate should I use?

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What is the best and most cost effective substrate for a planted aquarium? Jeremy Gay advises… What is the best and most cost effective substrate for a planted aquarium? Jeremy Gay advises…

Q: I’m setting up a new tank and looking for the best or most cost effective planted aquarium substrate.

I have two bags of planting substrate but on reading the packaging, it says it buffers the pH to 7. I am planning to keep fish that require a lower pH than this, so what would you recommend? The tank is 120x60x60cm with an external filter.

KEVIN SCOTT, VIA EMAIL

A: Jeremy says: You can try not using any planting substrate at all. Use a 7.5cm layer of any inert aquarium gravel or grit, plant it and then use a complete liquid fertiliser instead. I've done this many times and you'll be amazed by the results.

If you definitely want something nutritious, then pond soil could be used as a bottom layer, or mixed with sand to give it a lighter structure still. You will need gravel on top of it to stop it stirring up and making a mess, and you'll need to test beforehand to see if the pond soil affects the pH. Next would be a tub of substrate fertiliser, topped with gravel or grit, and that would just be a case of whose product goes the furthest for the money. Sera, Tetra and the Dennerle formulations contain peat, so should bring pH down if required.

Complete planting substrates and aquatic soils will always be the most expensive but you could just use them as a bottom layer with inert gravel on top, or even look for secondhand aquascaping soil and use that as a base layer. Most aquascapers will have buckets of used soil and I used to dry mine out and reuse it — it will allow for a low pH too.