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Old 01-23-2019, 04:27 PM
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Default No more cypress knees for me

Who would have thought that cypress knees would rot as quickly as grape wood? Not me. I have been on the glass bottom boats in Silver Springs in Florida and seen that boat at the bottom of the river that was made out of cypress by the Spanish explorers. I would have thought that cypress knees would have no trouble weathering conditions in a viv, but I was wrong.

I purchased some cypress knees in Summer of 2016. They were absolutely beautiful and I was really happy with them...for a while. Now, 2 and a half years later, they are falling over because the bases are all rotting. They are also squishy to the touch above the substrate level. To the best of my knowledge, they didn't come in with termites or anything like that (and I did bake them in the oven for a long time, just to be sure). It is just the wood rotting in vivarium conditions. I also bought several tanks from another dart frog keepers. He had bought cypress knees for his tanks, too. They are all rotting now, as well. So, it wasn't just the batch that I got.

The list of wood types that have held up well in vivarium conditions for me so far is Manzanita, Cork, Malaysian Drift Wood, and maybe some Mopani (maybe because my memory if faulty...). I don't recall having used Ghost Wood, so I can't comment on it.

Does anyone else have good experiences with cypress knees they can share? Was I just unlucky? Any other types of wood that have held up well for other people for 5 years or longer that aren't on my list?

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Old 01-23-2019, 04:31 PM
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Default Re: No more cypress knees for me

I wonder if some of the difference between submerged shipwrecks and knees in a viv is the ambient chemistry: vivs are fairly oxygen rich -- good for rotting. The bottom of a bayou is likely acidic and anoxic -- less rotting action.

I don't have any years-old vivs to compare to, but I like cork. Looks good, easy to work with, not too expensive, and sustainably produced.
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Old 01-23-2019, 06:00 PM
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Default Re: No more cypress knees for me

Greetings,

Cypress boats (and piers etc) are made from the trunk heartwood of Cypress trees. That wood is the strongest and densest the tree produces since it has to support the trunk. Being modified root structures with the purpose of helping the tree absorb oxygen in flooded environments, cypress knees are not heartwood nor, I would speculate, are they as soaked with preservative resins.
You can see the same difference in wood durability when it comes to redwood (a close relative of bald and pond cypress): Old growth redwood of the kind harvested a century ago is dense and highly rot-resistant. New redwood lumber from re-grown trees is only marginally rot-resistant and no where as dense as old growth.
I would use cypress driftwood (which is often trunk or heartwood) rather than knees for durability - you just can't always get that awesome, vertical tapering shape that cypress knees provide...
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Old 01-23-2019, 06:21 PM
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Default Re: No more cypress knees for me

I just use the hardwood driftwood around rivers here. Probably oak. Holds up really well
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Old 01-24-2019, 06:16 PM
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Default Re: No more cypress knees for me

Quote:
Does anyone else have good experiences with cypress knees they can share? Was I just unlucky?
Not unlucky - mis-application.

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vivs are fairly oxygen rich -- good for rotting. The bottom of a bayou is likely acidic and anoxic -- less rotting action.
This is exactly it. If kept fully submerged, the wood would have held up much, much better. Water pH doesn't have a ton to do with it - the principle holds in marine & estuarine, as well as fresh, situations (from sour to sweet fresh). Anoxic water helps a lot but even decent-DO water (e.g., in an aquarium) still slows the rot plenty. Whereas super humid but perfectly aerated is the very best way to rot anything.

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I just use the hardwood driftwood around rivers here. Probably oak. Holds up really well
Exactly. Mainly, I also just use freshwater driftwood I have found (assuming all the weak stuff, probably sapwood, has already been tumbled off - seems to work!). Just walk stream banks in low-water season and hunt the flood-debris piles. The hard part is finding small enough pieces with some character to them. There's plenty of huge stuff, and plenty of small straight pieces, but finding small twisty pieces requires some "shopping". You can also carry a saw to cut off fun parts of huge pieces. Most of this work, I do as part of field herping. Driftwood just goes in my pack, as I'm flipping & visual-searching for whatever it is I'm herping for. Most days I'll bring home one or two pieces. I have quite a stockpile now...a couple tubs of small pieces in the shed, and a little pile of bigger stuff in the yard.

To a lesser extent I'm using terrestrially-sourced manzanita and juniper (also field-collected by me). Roots and burls when I can find them, branches when I can't. Both of those genera work well in the long haul.

I simply cannot pay the prices asked for viv wood, except in the case of cork bark. There is no substitute for cork bark, and it's worth every penny. I just buy it in bulk, to get it a little cheaper.
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Old 01-25-2019, 08:47 PM
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I hope mopani hold up for a long time because I have multiple pieces in my vivarium. Almost a year old.
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Old 01-25-2019, 11:00 PM
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Default Re: No more cypress knees for me

had the same thing happen to me, had a viv set up for about 2-3 years with cypress knees and they "rotted" out and were mush if you touched them or try to move a plant off them. The plus is the iso's loved them and would find hundreds inside them.
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Old 01-27-2019, 12:29 AM
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Default Re: No more cypress knees for me

Another random thought maybe baking them actually made them more susceptible to rot, could be various chemicals in the sap that help preserve the wood were changed and no longer did that job. I have seen people build pretty serious vivs with the cypress knees and that would be sad if they rotted that quick.

I have used Malaysian drift wood a lot and baked it for all vivariums and it has held up well.
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Old 01-27-2019, 04:01 AM
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Default Re: No more cypress knees for me

In college, we looked at Taxodium distichum under a microscope and ran some experiments on the attached/live cypress knees. There is decent evidence mounting that they are false pneumatophores. they are false in that they are taxonomically different from other rhizomorphic structures which share common ancestry, but they serve the same functions as pneumatophores to a degree. The cypress knees apparently seem to have evolved independently of those other lineages, at least at the word of my professor and our lab books. The implications of this are that they have not evolved some of the same defenses as other aquatic/semi-aquatic trees. Cypress knees, by my personal reckoning, utilize high rate of exchange of gasses, mycorrhizae, and hypertonic xylem to protect from pathogens and environmental degradation. That being said, they might be extremely sensitive as to structural integrity by changes in conditions outside of those where the cells differentiated.

This is just some food for thought from a guy who does not specialize in the above areas of study. (I'm biochem)
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Old 01-28-2019, 11:42 PM
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Default Re: No more cypress knees for me

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The implications of this are that they (knee tissues) have not evolved some of the same defenses as other aquatic/semi-aquatic trees.
Oh that's fun. Interesting stuff, thanks.

Whereas other tissues in the species do appear quite chemically well-defended - there are many old homes and cabins in the SE with cypress-lumber components (framing, ceilings, siding, porches, etc) that have stood up well to the numerous and diverse wood-destroying organisms of the region.

It makes me wonder if Taxodium roots and branches would work better than knees for viv applications? Sometimes you can find a tip-up that's been blown over by a hurricane, or undermined by bank erosion. There's the roots. Much easier to source though, would be branch trimmings. Not much character to them, but you could probably at least get in a fork or two.
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Old 01-29-2019, 04:43 AM
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Default Re: No more cypress knees for me

That is definitely what i would guess. The true lumber portions or branches would be far better suited once dead and dispossessed of the living tree.
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Old 01-29-2019, 02:59 PM
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Default Re: No more cypress knees for me

That's really interesting stuff, guys. Thanks for the comments. It never occurred to me that different parts of the tree would be more or less susceptible to rot. While I think you guys have nailed the reasons for the problem, it still means that, as cool as they look, cypress knees might not be the best thing to put in our vivs. Unless maybe we seal them somehow that doesn't make them look shiny? I think I am out of the cypress knee market, regardless. There are, as you have pointed out, much better options out there :-)


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