Void space in driftwood

[Erik G]

I have a large piece of driftwood (think of a trunk with roots kind of look) going into a 75 gallon planted aquarium that has some decent void void/hollow space inside. I'm thinking to fill/seal it up with Great Stuff for ponds. My concern is that it might make it somewhat buoyant. I was thinking to possibly fill it with gravel/rocks before filling/sealing to add some weight. Wondering if anyone has had any experience with this before?

[Expectorating_Aubergine]

Why do you want to fill it? Seems like something pretty desirable. Depending on what kind of fish you have in there, they might dig it all out (I had a cichlid do that once).

Edited January 26 by Expectorating_Aubergine

[Odd Duck]

On 1/26/2023 at 11:28 AM, Erik G said:

I have a large piece of driftwood (think of a trunk with roots kind of look) going into a 75 gallon planted aquarium that has some decent void void/hollow space inside. I'm thinking to fill/seal it up with Great Stuff for ponds. My concern is that it might make it somewhat buoyant. I was thinking to possibly fill it with gravel/rocks before filling/sealing to add some weight. Wondering if anyone has had any experience with this before?

That sounds like a pleco cave to me.  😃  Can you show us pics or explain why you want to fill it?  It might make a difference on recommendations.  I’ve not filled and capped anything, so I may not be much help on this one.  I like to offer hiding places to bottom dwellers.

[Theplatymaster]

On 1/26/2023 at 7:11 PM, Odd Duck said:

I like to offer hiding places to bottom dwellers.

not just bottom dwellers, my platies will explore into my coconut hut. Livebearer females like to have hiding spots to give birth, even fish that are being bullied like hiding spots. My perfectly healthy panda garra also likes to go into my coconut hut, same with my betta

[Odd Duck]

On 1/26/2023 at 6:21 PM, Theplatymaster said:

not just bottom dwellers, my platies will explore into my coconut hut. Livebearer females like to have hiding spots to give birth, even fish that are being bullied like hiding spots. My perfectly healthy panda garra also likes to go into my coconut hut, same with my betta

Yep, all that and more, I’m just a bit more focused on bottom dwellers.  But I do understand not everybody wants voids/caves/hides.  So that’s why I was asking @Erik G’s goal(s).

[Rube_Goldfish]

On 1/26/2023 at 12:28 PM, Erik G said:

I have a large piece of driftwood (think of a trunk with roots kind of look) going into a 75 gallon planted aquarium that has some decent void void/hollow space inside. I'm thinking to fill/seal it up with Great Stuff for ponds. My concern is that it might make it somewhat buoyant. I was thinking to possibly fill it with gravel/rocks before filling/sealing to add some weight. Wondering if anyone has had any experience with this before?

When I bought a fairly hollow log, the person at my LFS warned that I might want to plug it with filter floss or coarse sponge so that a fish couldn't get stuck in a spot where it couldn't turn around and get back out. As it turns out, I stuck a rock more or less on that spot when I first set the tank up to weigh the wood down. It no longer needs the rock, but I ended up liking the way it looks, and the Amano shrimp have their own hideaway (they can squeeze in the hollow just fine).

All that to say, if you want to plug it up, I'd try sponge or filter floss before the Great Stuff; at least you know it won't be buoyant and it would still allow flow.

[Erik G]

Yeah, it's a space inside the back of the piece. It's already going to give my plecos and bottom dwellers plenty of spaces to hang out, so I don't want them to have this one to never come out of 😉. I've wedged a couple stones in there to help weight it down and take up some space. I may just go with something inert like filter floss or a piece of filter media cut to fit.

Thanks for the replies.