Guide 25 — Botanicals Guide

Alder Cones & Botanicals

Small dried cones with an outsized role in shrimp and snail keeping. This guide covers what alder cones actually do in the water, how to use them, and where botanicals fit alongside — not instead of — good maintenance.

What an Alder Cone Is

Alder cones are the small, woody seed cones of the alder tree (Alnus glutinosa), widely used across freshwater keeping — most commonly in shrimp and snail tanks. When added to water, they slowly release tannins and other plant compounds, in the same way that dried leaves, bark and other botanicals do.

They sit alongside other commonly used botanicals such as Indian almond (Catappa) leaves and various barks, all of which work on the same basic principle: submerged organic material leaching tannins and trace compounds gradually over time.

What Tannins Actually Do

Tannins are the compounds behind the tea-coloured "blackwater" tint that steeped cones and leaves are known for. In the aquarium, their most visible effect is that colour change — but the practical reasons keepers use them go a little further.

• —  A gentle, gradual softening effect on pH in low-hardness water, similar to how driftwood and leaf litter behave in nature
• —  Mild antibacterial and antifungal properties, widely reported by breeders as supportive during shrimp moulting and general condition — though this is a supplement to good husbandry, not a substitute for it
• —  A surface that colonises with biofilm over one to two weeks submerged — a genuinely useful grazing food source for shrimp and snails
• —  Cover and a more natural-looking aquascape element, particularly in blackwater-style setups

How to Use Them

Most keepers rinse cones briefly under cold water before adding them, to remove surface dust and debris. Some choose to boil or steep them for a few minutes first — this softens the cone, speeds up the initial tannin release, and reduces the amount of anything sitting on the outer surface, though it isn't strictly necessary if the cones are from a reputable, aquarium-safe source.

A cone can simply be dropped into the tank and left to do its own thing. It will initially float, absorb water over a day or two, and then sink. Once waterlogged and colonised with biofilm, most keepers leave cones in place until they visibly break down, then replace them — there's no fixed dosing rate, and the right amount comes down to how much colour and softening effect you want in your specific setup.

A Note on Water Hardness

The softening effect of tannins is genuine but gentle, and it works by influencing pH — it does not meaningfully reduce general or carbonate hardness on its own. In already hard or heavily buffered water, the effect will be barely noticeable. Cones are a complement to your water chemistry, not a way to override it. If you need to adjust GH or KH directly, that's a separate process — covered in our GH & KH guide.