Specific gravity of various pond plants.

[VABeachPondGuy]

I'm building an Excel spreadsheet designed to calculate the weight of various pond materials in and out of the water. Most items are easy except for the plants. It's safe to assume that most pond plants less any soil clinging to the roots have a sg of less than 1 but I wonder if a botanist or ecologist with way too much time on his hands has figured out a way to measure that kind of biomass.

Any thoughts?

 

[addy1]

Interesting project, can I as why you would want to know this?

 

[HARO]

Way too much time on his hands! John

 

[VABeachPondGuy]

I'm designing a suspended planting bed for areas of the pond where there is no asthetic advantage to having rocked walls. It will also be great for people who like the look of a tiered pond but don't want to sacrifice water volume. The spreadsheet will tell me how much buoyancy to build in based on the amount and type of planting medium and plant material per square foot.

Submerged and floating plants are easy to fugure but marginals are a different story. I could guestimate but what's the fun in that when I've already gone to all the trouble to asemble the other data?

 

[HARO]

I rest my case. John

 

[taherrmann4]

What if you got a fish scale and made a basket that hooked onto the scale, then put the marginals in the basket underwater and see how much they weigh.

 

[VABeachPondGuy]

Yes John, I have too much time on my hands and I need to shake the dust off of my brain for a change. I may resort to weighing them if I don't find a formula somewhere else. I've reached out to a few of my marine biologist friends who will also likely think that I have too much time on my hands, lol.

 

[HARO]

No offense meant! :wink: But seriously, would the specific gravity of a plant not vary with the percentage of leaves / roots / stems? That would mean that the s.g. of a given plant could change as that plant grows. John :twocents:

 

[addy1]

Yes John, I have too much time on my hands and I need to shake the dust off of my brain for a change. I may resort to weighing them if I don't find a formula somewhere else. I've reached out to a few of my marine biologist friends who will also likely think that I have too much time on my hands, lol.

lol keeps the cells from getting hard and dieing! they say thinking, using the brain is the best defense against dementia

No offense meant! :wink:

I am sure none taken...................

 

[VABeachPondGuy]

No offense taken. I can figure an average weight for the plants once I have a starting point. The only plant material that would factor into the calculation is the parts standing above the water and bearing down on the stem and roots below because those parts below the surface are close to the same sg of water (1). The point of the exercise is to make sure the finished assembly is slightly buoyant but not so buoyant that extreme measures have to be taken to anchor it in place underwater.

 

[VABeachPondGuy]

I mean it would be nice to have the sg of marginal plants but the weight above the surface is probably more important.

 

[minnowman]

the weight of the planting medium which is above water will probably be more than the plants, because it will wick up water.