Why Aquarium Water Harms Carnivorous Plants & Proper Sundew Division Techniques

The Problem with Aquarium Water

Using freshwater aquarium water for carnivorous plants—even clear water from well-maintained tanks—is detrimental. While it may lack visible waste, aquarium water contains high levels of dissolved nitrogen compounds (ammonia, nitrites, nitrates) from fish metabolism and decomposition. This essentially acts as liquid fertilizer, which burns the sensitive roots of carnivorous plants adapted to nutrient-poor environments. Additionally, the organic load promotes bacterial growth in the soil, leading to foul odors and potential root rot.

Better Water Alternatives

Tap water that has sat out to dissipate chlorine/chloramine may be acceptable only if its total dissolved solids (TDS) are below 50 ppm. Test with a TDS meter or aquarium test kit. Otherwise, use rainwater, distilled water, or reverse osmosis (RO) water.

Dividing Spoonleaf Sundews (Drosera spatulata) Successfully

Separating small plantlets from a mother clump requires patience to avoid root damage:

1. Gently remove the clump and submerge roots in a bowl of water to wash away soil.
2. While roots are underwater, carefully untangle individual plants—the water supports delicate roots and reduces breakage.
3. Alternatively, divide the clump into 2–3 larger sections rather than separating every tiny plantlet. This minimizes transplant shock.
4. Repot immediately into a 1:1 peat/perlite mix and keep moist with pure water.

Young sundews recover slowly from root disturbance; expect a month or more for full recovery.