Lava filter.

[vertigo72]

Hi all,

Im still struggling how to make a skimmer and increase my ponds filter capacity, and I came up with the following, simple idea:

Thats a cross section of my pond. The dark red line is a brick wall thats already there, its well below the water line. It creates a bassin though fish can (and do) swim over the wall. I would simply fill it with lavarocks, put some pipes in it, and pull water from underneath with a pump, and pump that to my biofilter.

Some pics that may help for perspective:

You cant see the wall there as its under water, but its the right "lob', roughly the same size as the bog where my irissen grow. Im guessing I could put roughly 1500 liter (400 gallon) of lavarock in there without going higher than the wall.

The idea is to make this a place where I can put as much plants as I want, with ca 15-20cm (6-8 inch) water above it. By pulling water at the bottom and forcing the water down (rather than the other way as usual), it would also act as "skimmer". Floating debris would collect there so its easier to scoop up, if its not broken down. Not quite a super skimmer, but better than nothing I gather. And nice side effect is that I can pump the water to my biofilter and waterfall after it has been through the lava.

Any thoughts? What size lava should I look at, or doesnt it matter?

 

[koiguy1969]

sounds like your pond may benefit from it, (lots more bio media) ...you may have to remove and clean the lava rock every year or two.
you plan on drawing from the bottom of the pond also?

 

[vertigo72]

Im already drawing from the bottom, though no bottom drain. I have a 15K liter /h pump (4000 gallon) at the lowest point, pumping to my DIY biofilter, and a unknown, I think 5-8K liter pump (2-2500 gallon) also pumping from the bottom to an UV and then the iris/clay bed on the left, which overflows back in to the pond. For this lava bed I have another 8K liter pump available. The pond is supposed to be ~50.000 liter.

As for cleaning those rocks.. could it really clog to the point of not letting water through, or just clog so that you lose biofiltration? Either way, once a year or two, I can live with that.

 

[fishin4cars]

If you haven't used lava before, fill a five gallon bucket up with lava rock, place a sponge, batting anything to screen the water and a place for the water to come out. It will have dead spots and smell horrid in two to three weeks. the only good way I could see using lave for a filter is through a drip/shower type system. It works for filtering I won't argue that but I was glad to get away from it when I stopped using it. I had it in my first DYI and within two seasons I scrapped that idea!

 

[vertigo72]

Indeed, Ive never really used lava before. I have a few rocks that I dont even recall where they came from, that I threw in my biofilter, and I dont notice anything particular about them..? Also my neighbour has about 1 ton of lava in his filter, similar setup to what I plan, and it seems to work nice, not smelly. Pond is 3 years old now I think. He's never washed them (though I suspect he should).

Anyway, what would you suggest instead then? Gravel or pebbles ?

 

[fishin4cars]

If I were going to go that route, I would probably first try and find a way to keep anything off the pipes so you have good water flow under all that, that's not a place you want stagnant areas. Once you get a layer of something above I would go a layer of medium river rocks, then smaller pebbles, then small pea gravel mixed with Kitty litter or koi clay, this would be a perfect bog area. I would also consider possibly reverse flowing it. This would keep the bed cleaner and less chance of anerobic and also serve as a good filter/ bog/ plant medium. Only thing would be keeping the pump from injecting chewed up leaves and such as reverse flowing wouldn't work well that way. A good sponge filter on the inlet side of the pump drawing from the pump and kept clean would provide perfect enviroment. lava can be used but for this application I would say, NOT the best choice for sure. IMHO

 

[vertigo72]

Good points. Lifting is not going to be easy though :S, its not like the bottom is flat. I was planning on a mesh of pipes to avoid the worst, and since the area is shallow for the most part, I dont think it will be a big problem. I could also add some air tubes in there, I got ample aerating capacity, Just not sure if plants like air bubbling up.

 

[fishin4cars]

I'm not sure on plants planted in substrate either but in filters they are putteing hyacinths and lettuce in the area's that bubble up and they do great. The main plants I would be concerned about planting in bubbling substrate would be lilies and Lotus's. pretty much anything else I don't think it would really bother but may actually increase growth rate.

 

[vertigo72]

hyacinths dont seem to like my pond. Or perhaps the water was too cold when I put them in. The only 2 that somewhat survived seem to be doing slightly better now, we will see if are keepers or not.

As for lilies, I dont think lilies would survive in substrate anyhow, do they? I always put them in clay baskets. Regardless, I have no idea what Ill plant there yet, dont know much about water plants, but I think Ill put them in baskets anyhow. Many of them will need to be moved inside for winter, so.

Anyway, looking for something I can use as support grate now. I found some galvanized grates that would be perfect, but I assume galvanized means zinc and I gather thats not a good idea. Cant find anything plastic

 

[koiguy1969]

bread delivery trays?....sometimes you'll find them stacked behind supermarkets.

 

[fishin4cars]

don't know if anyone in your area will have them or not but they make a grating that goes in the bottom of dog kennels. It's tuff and plastic but has a lot of holes in it for passing through for clean up. I have even seen some people using it for the bottom of their DYI filters.

 

[koiguy1969]

thats good stuff, fishin'...but i hear its pricey!

 

[vertigo72]

I found some plastic stuff at an online koi shop. Not very cheap, but affordable. Still looking for a cheaper alternative, as, well, Im a cheapskate Ill go visit a few shops tomorrow that sell stuff for farmers, as such grates are apparently used for pigs as well.