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Alfragrog as soil substitute

millertime9

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1 Jan 2023
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16
Location
Glasgow, Scotland
How does this work?
I like the idea of it, but all I can see online are balls of it, how does that work with the roots of plants? Doesn't seem secure?
 
How does this work?
I like the idea of it, but all I can see online are balls of it, how does that work with the roots of plants? Doesn't seem secure?
Alfagrog is better suited as a filter media as opposed to a substrate.

Having said that, I did put a layer of alfagrog in my big tank substrate last year instead of lava rock. I wouldn't use it as a solo substrate though, it's much too coarse.
 
I notice this is in the ponds section so am guessing you are wanting it for a pond and not a tank. For ponds it's more of an option but I don't think you really benefit much. I've used it for emersed plants in aquaria and all it does in those situations is anchor the plant in the pot. It will work the same in a pond but isn't as secure as aquatic soil and the plants can be disturbed before they root securely.
You can grow pond plants without any substrate at all and many of mine are just chucked in or tucked in the margins but they do best when grown in soil as it provides some nutrients and gets them established quickly. I personally would keep the alga grog to the filters.
 
Ah ok thanks maybe I misinterpreted what people said

My thinking was it would be lighter weight for hanging into the pond with fishing wire, but also maybe better for the water than soil too
 
Do the roots, like in lillies for example not need soil or something to anchor into?
Am I overthinking it and plants can just go right into the water!?
 
Do the roots, like in lillies for example not need soil or something to anchor into?
Am I overthinking it and plants can just go right into the water!?

For water lillies in a wildlife pond they are probably best planted in baskets with aquatic soil but in fish ponds they seem to thrive when just tied to a brick and thrown in (they still send down root's which eventually find the sediment in the bottom of the pond if you habe any). If you want a nice pond then it can pay to get it right and aquatic soil in pots is the best way to go, especially with lillies as you can add root tabs to feed them.

With iris or vigorous plants like sedges you can just wedge them in and they will root to the profile of the pond. It certainly isn't best practice but it does work. If you only have a few plants though I would pot in pond soil.

I've not used fishing line for plants, I pot them and if they are to deep, raise them on bricks. If the pot becomes unstable or top heavy I do attach wire to the pot and anchor it outside the pond though. It's mainly because my shelfs were built for smaller plants as it was a fish pond first. Adapting something is always a fiddle.

I'd bet there are people that use alfa grog in the way you mention bit I've not seen it done and I don't think you'd get much more benefit than if you used shingle.
 
For a new wildlife pond with little in the way of sediment, I'd opt for pond soil and pots, at least for the first few years. In an established pond, with plenty of sediment, wedging them in is fine and is what I do. I've also made baskets from chicken wire lined with landscape fabric to overhang. You can make these with a long lip to peg into the soil a distance back from the pond edge.
 
For a new wildlife pond with little in the way of sediment, I'd opt for pond soil and pots, at least for the first few years. In an established pond, with plenty of sediment, wedging them in is fine and is what I do. I've also made baskets from chicken wire lined with landscape fabric to overhang. You can make these with a long lip to peg into the soil a distance back from the pond edge.
Ah I like the sound of that
Any chance of a pic or two?
 
This is a really crap photo, and not quite as I described as this was a prototype which wasn't incredibly successful. Mainly due to the lip to go over the pond edge being too short and being unable to peg it into the rubble below! It's basically just an envelope with the sides tied together. I'd do it the way I described next time, especially if I had soil to peg into. Not sure you can see it very well, but it's what the Marsh Marigold is sat in.
20230107_113256.jpg
 
This is a really crap photo, and not quite as I described as this was a prototype which wasn't incredibly successful. Mainly due to the lip to go over the pond edge being too short and being unable to peg it into the rubble below! It's basically just an envelope with the sides tied together. I'd do it the way I described next time, especially if I had soil to peg into. Not sure you can see it very well, but it's what the Marsh Marigold is sat in.
View attachment 199529
Ah I see what you mean
So not actually making a pot shape out of it?

Does the soil not just wash away though and are you not worried about the liner or the fish, as the chicken wire can get sharp/rust?
 
It does make a pot shape when you weave the two sides together. Lined with landscape fabric, the soil can't wash away; this one is filled with gravel as opposed to soil. As for sharp edges - those are tucked inside when the edges are tied together. The cut edges on this one need some modification and I'm redoing it in spring. All trial and error lol, but the idea works and would work better if I didn't have a ton of rubble preventing me from pinning it down and if I had made a longer lip to go further out of the pond and over the edge. For me, because I'm retro-fitting and have a rockery area instead of lawn/soil there, pegging is difficult.
 
Hard to put to words, but Alfragrog or sintered glass is like porous popcorn-shaped glass. For large pond plants in pots that can be handled individually, it's ok stuff to use. As a substrate in a tank where the tank bottom is the entire pot actually, the shape of Alfagrog will make it difficult to get the tweezers and plant in. The harder you will try to push it in the denser the Alfagrog will hook into each other preventing it. It's even difficult to stick a finger in it.

I use it in the garden in the helophyte filter, and if I want to replant something I need to take half of the grog out of the pot, put the plant in place and put it back on top.

I wouldn't want it in the tank as substrate, it would be a disaster the get it planted...
 
First time l heard of Alfagrog when l read Stuart Thraves book Setting Up a Tropical Aquarium Week by Week
I think the books aim is to help prevent the mistakes mades setting up a new aquarium as regards cycling adding fish and plants. He doesn't break the budget with high end gear,at all andin the planting chapters he decides on Alfagrog as substrate and going through the usual problems eventually has much sucess with the plants.
 
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