I don't think I even need to explain what Catappa is now, says Nathan Hill, but just to recap it seems that all things from the Terminalia catappa tree (or Indian almond tree) are teeming with antibacterial, antifungal and even a little antiparasitic compound.
So why bark? Well, I’d raise two points. The first is this stuff lasts and lasts compared to the leaves that you’ll get a couple of weeks out of at best in a densely populated shrimp set-up.
The second point is that it seems to contain a lot more tannin than the leaves alone do. Get a bottle and stick a couple of pieces in, and then do the same with a couple of leaves and compare after a week. You’ll see a difference.
The instructions say to boil for five minutes prior to use, but I’d say this is optional. In fact, the only thing it really does is speed up the sinking time, which can be a few days if left to its own devices.
They also advise to replace after two to three weeks, but unless you’ve got a plague of shrimp that could strip a human body in hours, then I think you’ll get a lot longer.
Besides, even once inert, there’s nothing offensive about the pieces of bark, and scattered on a natural looking tank they blend in with leaf litter and other debris nicely.
Dosage is quite important, and some users have reported outbreaks of slime on fish, gasping and distress (so basically all the symptoms of your typical pH crash) but only when being liberal with the amount added.
The packaging recommends one piece per 120 l., and with a little careful cutting with scissors, you can soon scale pieces down accordingly for smaller tanks.
£6 might be a little harsh for 20g of wood, but I’ll concede that it does what it’s supposed to. As it is, it’s right on the cusp of what I’d pay out.
Price: £6 for 20g (around nine pieces of bark). More info from hobbyshrimp.co.uk
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