2Hr Aquarist APT Jazz

APT Jazz works in both, but the results differ, and it's worth understanding why. Aquasoil (and other substrates high in organic content) binds ammoniacal nitrogen and holds it in the root zone, where plants can draw on it steadily.

Inert substrate doesn't bind nutrients the same way, so a root tab placed in coarse gravel mostly leaches into the water column rather than feeding the roots - which defeats the purpose of root fertilising.

If you're on inert substrate, choose a fine grain (under 2mm) with at least 4cm of cover, and Jazz's added clay will help by improving the substrate's ability to retain nutrients. But for the fullest growth forms, Jazz is designed to be paired with aquasoil.

Plants take up ammoniacal nitrogen very efficiently through their roots, and it drives noticeably faster, more robust, fuller growth than relying on the water column alone. Fresh aquasoil is rich in it, which is why plants grow so well in a newly set-up tank, but most aquasoils deplete their nitrogen supply within 3 to 6 months.

APT Jazz slowly releases ammoniacal nitrogen back into the substrate, letting you rejuvenate matured aquasoil so it performs as if it were new, without tearing the tank down. It also enables Nitrate Limitation: by feeding nitrogen at the roots while keeping water-column nitrates low with APT liquid fertilisers, you can unlock the deepest reds in species like Rotala.

Unlike terrestrial "osmocote"-type tabs, Jazz is engineered specifically for underwater use, so it releases over months rather than dumping its contents in weeks, and won't cause ammonia spikes.

Push the capsule into the substrate directly under the root zone of the plant you want to feed, at least 2.5cm (1 inch) deep, using roughly one capsule per 2.5 square inches (16cm²) of substrate. Focus on heavy root feeders - Crypts, swords, and stem groups you want to thicken.

Siphon out any detritus stirred up during replanting. Results show on new growth, usually within about 7 days: root uptake is slower than leaf uptake, so existing older leaves won't rejuvenate - watch what comes in next. A single dose lasts around 2 months before it's worth replenishing.