Fish owners, rejoice! That (rather pungent) tank clean you have to steel yourself for every so often can double up as a clever gardening hack. As rumour has it, fish tank water is a brilliant source of nutrients to pour over leafy green plants in your garden.
So, next time you’re cleaning and removing water from your aquarium, be mindful of the fact that this stuff is essentially liquid gold for gardeners.
There are some dos and don’ts, of course, but the water from most freshwater fish tanks can be a great, mild, and natural fertilizer not just for your garden, but also for indoor plants such as herbs. Interested? Now considering buying some fish? Me too, actually. Here’s what else to know…
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How exactly can fish tank water help plants?
Here’s the very simple reason why: old fish tank water contains fish faeces, which is mainly ammonia. This waste converts from ammonia into nitrite, all thanks to either the filter or gravel in the tank. And as we all know, nitrogen is a form of plant fertilizer. So, not only will this water hydrate your plants, but they’ll get a much-needed fertilizer boost at the same time.
It goes without saying, but we’d only suggest giving this water to plants that are in need of fertilizer. Avoid pouring this water on plants that you’ve recently tended to — because excess nitrogen can harm plants, causing very rapid growth that may threaten the quality of your produce.
If your fish tank is placed rather close to the exit to your backyard, you’re winning — this makes it a less stressful job of worrying about spilling this smelly water on your floors.
Better yet? This gardening hack doesn’t just mean more water for your plants, but it means you’re throwing away less water each time you clean your tank. Instead of throwing it down the drain, pour it into your watering can and make good use of it in your backyard.
Which plants to focus on the most when working with fish tank water? If we’re thinking of the ones that will get the most benefit, then focus on herbs like basil, mint, parsley, coriander and rosemary. When it comes to vegetables, tomatoes, peppers, lettuce, spinach, and cucumbers will love fish tank water. Your fruit plants needn’t miss out either: strawberries, raspberries, blueberries and citrus plants will all love this extra nitrogen boost.
Produce isn’t the only thing that you can use this gardening hack for. If you have a rose bush or plant, then you’re winning. The same goes for hydrangeas, lavender, marigolds, and geraniums.
Maybe now you can rethink the kids asking you for a pet once a week!
Final thoughts
It should be noted, though, that this isn’t the rule with all fish tanks. Only freshwater ones. Saltwater aquariums don’t follow the same rule, so we wouldn’t use this for watering your plants since the salt makes it harder for the roots to absorb water.
Be mindful if you’ve recently added any chemicals or medication to your tank. If you have, check whether what you’ve added claims to be “plant safe”. If you’re still unsure, then it’s best to avoid using it on your plants until you’re sure it won’t hurt them. Definitely avoid using the water if you’ve used any copper-containing treatments in your tank recently.
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