Water void stock tank bog with grates

[velokoi]

Yes another person with a bog design question. I have been reading many of the other posts, but still have some questions.

I bought 6 100 gallon stock tanks (52"x30") to use as upflow bogs, but instead of 2 or 3" pipe at the bottom with a clean out I want to use a system similar to the upflow purchased waterfalls and create a 8" water void at the bottom using a fiberglass grate or even a plastic pallet. Most of the designs I see here use the pipe with holes and a cleanout, is the water void method a tried and failed approach, or does this design have merit?

I would have two 2" bulkheads at the bottom, one for an in from the skimmer and one for a drain going to side of the pond both located in the bottom of the 8" void, then 4" of 2-3" river rock (because the grates are 1" gaps) then 10" of 3/8 to 3/4" pea gravel for the plants and a water fall out through a stream for some and secondary bog for others to the pond. Also thinking of adding some type of mesh between rock layers to keep the pea gravel on top, I know it will move around.

This is not my first go, I have about 10 DIY ponds between 500 and 5k gallons with many many mistakes under my belt. I am sure I am going with the bog design (stock tanks already here), just not sure about how I want to deal with cleaning the bogs and the water void design is something I have used a number of times on a smaller scale with good results. IMO the water void makes cleaning easier, I have just never tried it on this large of scale and most designs here and on the web use the clean out pvc pipe method.

 

[j.w]

@velokoi

 

[Mmathis]

Hello and welcome!

Are you talking about a system similar to Aquascape’s centipede and snorkel system?

 

[velokoi]

Similar, but the only access to the void/reservoir would be via two bulkheads. One bulk head with water pumped in and one with a valve to release dirty water as needed. No pvc pipes, clean out or snorkel in my current design, just a grate above water holding up gravel.

I patterned it after the typical waterfall filter, but replace filter media with gravel and plants and increase size to a 100 gallon stock tank.

 

[velokoi]

 

[Hound Heaven]

The one thing that jumped out at me was drawing the return water from the bottom of the tank. I would draw it from the top. Good luck.

 

[velokoi]

I am drawing from the top via a water fall, the bottom out is a valved drain/clean only so I can full flush the both water void at regular intervals.

 

[velokoi]

After a week of searching for the grates that are reasonable and workable I found dura bench greenhouse shelving to keep the rocks off the floor of the container. I am going to try this over the plastic pallets, fiberglass grates or the Benchmaster garden shelving because of both cost and apparent workability of the material. I have a single fiberglass grate, which will be stronger I assume, but looks hard to work with and brittle, Benchmaster costs too much to ship, but looks much stronger. If this fails my testing I will have a new set of benches for my wife to garden with.

This will keep the cost of plastic for each bog at just over $100 each. $75 for the 100 gallon tank, $25 for the Grate and $24 for 2 bulkheads (2"). I am still trying to avoid using PVS/ABS pipe inside for water distribution to make cleaning debris easier and increase the size of the void. But that route is still my fall back, and then I will just need to decide on 2" PVC or 3" ABS piping.

I know these will need some serious support (bricks) to hold up the weight of gravel at around 75-100# per cf foot and I am expecting at least 8 cf per bog, so at least 800 pounds of weight. If this fails I plan to fall back to pipe, PVC seems to be the choice for most here, is ABS bad to use inside a bog?

www.greenhousemegastore.com/products/dura-bench-plastic-benchtop-2x4

 

[velokoi]

Another question, is there a preferred media other than pea gravel for a bog? My design is very similar to the sticky "DIY stock tank filter" from KoiKeepr, but I have not been thinking about the filter media vs pea gravel. Most/all bog mention some type of smooth stone for the bog. But I have had other materials, bio balls and filter matts grow great plants (on accident) as well. So if I change out the pea gravel for something lighter, all the better to me if something goes wrong and to ensure the grate does not fail.