ferts in a filter bag?

if you are talking about a canister filter, you need the little balls so that benificial bacteria can form and take hold
the other problem is, having root tabs outside of the substrate would basically only benefit plants that take their nutrients from the water column, so mainly stem plants
However, I do wonder if this could be an idea for how tanks with HOB filters, just shove a few root tabs into the hob so that you can essentially slowly release ferts into the water column...(shrugs)

In a filter, fertilizers like osmocote will deplete RAPIDLY. This isn't a good idea.

Osmocote isn't designed to be fully submersed as it is. If you put it in water flow it will be empty in days.

Read this thread in Barr's report...Post # 19.

http://www.barrreport.com/showthread.php/6571-Poor-Man-s-Pfertz-Dosing-(PMPD)/page2

Interesting.. thank you Joraan for the redirect. Those results were amazing, but it cant be that simple... Can it? And he was using handfuls of the stuff?

As far as the ferts being released quickly, i was thinking maybe a tablespoon/week per 10 gallons?
20ish percent water change with that dose?

Adjusted as need be down the line..

Bump.

Has anyone tried putting osmocote (not plus) in a canister filter? Will it leak massive amounts of ammonium?That one person from the Barr report posting seemed to have great results.

Well, it is going to depend on how much you put in there.
Remember that garden fertilizers are designed to work in a relatively dry setting. When you irrigate, some fertilizer is released. Then the soil dries out and no fertilizer is released. The plants use the ferts made available when you irrigated. Then you irrigate again, releasing more fertilizer.

In an aquarium, especially in the main water flow, the fertilizer is exposed to "irrigation" conditions constantly, so is constantly releasing fertilizer. This is fine if you want water column dosing, and add only a few pellets at any one time.

Part of the idea of using slow release ferts is to get the tablets (or little round balls) deep under the substrate so there is less fertilizer in the water column. Some ferts will trickle up anyway, so there is a combination of substrate dosing and water column dosing. If you set up the fertilizer in the filter you are simply water column dosing.

HypnoticAquatic turned me onto this idea earlier this summer. :biggrin:Thanks!

I put the equivilent of a 00 capsule at a time into a cut-off section of black pantyhose and sit that on top of my spraybars. Replace the O+ once a month +/-. So far, I am happy with the results (my 20 gallon journal is linked in my signature).

I also should mention that my tanks are dirted and I infrequently dry dose N P K.