you want Rocks in the Bottom of your Pond??
(by Ponds Plus)
There's a big company from up north that goes around conducting short
four or eight hour seminars on how to build a pond using their products and
design. It’s a cookie-cutter approach which makes all of the ponds
look pretty much the same.
After attending the seminar, Joe-the-local-lawnmower-guy-with-his-office-in-the-front-seat-of-his-pickup-truck is now "trained" and "certified" to design and construct a koi pond or water garden.... "poof"...... instant knowledge and ability (yeah right) and armed with a very comprehensive and well done advertising package. The seminar graduates in our region had never owned, kept, or built a pond prior to the seminar.
The system they’re taught to install consists of a skimmer, pump, waterfall filter, liner/underlayment, and enough rock/gravel to provide a 2" to 18" deep layer across the entire bottom and sides of the pond. The equipment used is not bad, though there are more heavily constructed versions of them available from other suppliers. The pump used is a VERY high amperage pump (costs $20-40 per month in electricity) and tend to fail in less than 2 years. The filtration in the waterfall is based on a few foam pads and a couple of large bags of lava rock, a technology that dates from the 60’s.
The project is completed in a single day and fish/plants are added immediately. Water is drawn into the skimmer by the pump and sent to the waterfall. At the end of the day, the project can be literally BEAUTIFUL. The water is often dirty and muddied, but that will settle in a few days. It's all remindful of a cool mountain stream somewhere in the Rockies....... But will it last?
"What the Salesman didn't manage to Tell You!"
Up north, where this system got it's start, the ponding season is only 3-4 months long and a summer daytime high of 85 degree's is a rare killer heatwave. In Southeast Texas we have often have an 11 month ponding season and normal high temps in the 90+ range all summer long! Things which may work smoothly and easily up north have to be done a bit differently down here.
The salesman often forgets to mention that to keep this pond clear you must add large amounts of beneficial bacteria (also sold by the salesman....). Around here, they tell folks to add the recommended total dose every day for several months until it clears up, then once or twice a week for the rest of your life. This can average between $400 and $600 PER YEAR in costs of bacteria additives. Failure to add the bacteria means that soon all of those pretty rocks in the bottom will be covered with grunge and algae.
The salesman casually mentions that you have to clean the pond only once a year.
What he doesn't say is that to "clean" the pond you must remove all plants and fish to a safe temporary location (VERY stressful, especially as the fish get older and larger), drain the entire pond, stir/pressure wash/clean EVERY bit of muck and nastiness out of the 6-8 ton pile of gravel and rocks in the pond bottom. This process literally takes a full day of pressure-washing and draining, over and over, until you get it clean.
Then you have to "rebuild" the entire pond and go through the "new pond syndrome" start-up all over again, EVERY TIME.
The salesman also doesn't tell you that this only has to be done up north once a year if the pond has no more than 3 or 4 fish and they are NEVER fed.... With a "normal" fish load, supplemental feeding, and a southeast Texas climate the pond may need to be drained and cleaned TWICE a year.
The installer will usually be happy to handle that little maintenance chore for you.... at a cost of $300 to $600 each time!
Why Rock Bottom Ponds Fail
Ponds tend to accumulate lots of dust, pollen, dirt, fish waste, leaves, bugs, and other debris. In a well designed system, the debris and organic waste is removed from the pond by the filter. The dissolved fish organics are processed by the beneficial bacteria in the pond and filter (which is only done efficiently in the presence of well aerated water).
In a rock bottom pond, there are thousands of tiny little void spaces down in the rock and gravel where organic debris accumulates. As soon as this debris becomes thick enough to block the continuous flow of aerated water through it, anaerobic metabolism begins to break down the crud. The easiest way I know of to explain the difference between aerobic and anaerobic bacterial breakdown of pond organics is to point out that aerobic processes are extremely efficient and produce little or no toxic by-products. Anaerobic metabolism is "rot", a VERY inefficient process which produces toxic sulphides and methanes as by-products.
Proof of this explanation is simple as can be. Find a pond constructed with loose rocks and gravel across the bottom. Wade out into it and reach down. Dig down a bit and pull up a rock from the bottom of the pile. Turn it over…. Notice that black oil-like nastiness? Take a whiff…. Notice that odor of rotten eggs? Fail to clean those rocks every single year and you'll end up with a toxic cesspool filled with dead fish.
Can these Rock Bottom Ponds Work in Southeast Texas?
The short answer is "yes", they can work. We consider them too expensive to maintain and believe they require HUGE amounts of physical labor, but they can work.... if you follow the directions. That’s the last problem we’ve found with the installers of these systems…. They never give you the “directions”.
The directions include:
very low fish stocking limit (1 goldfish for every 500-1000 gallons). We do not recommend stocking koi in these ponds under any circumstances.
do NOT feed the fish, they'll survive just fine munching on things in the pond. The system cannot handle the extra waste which occurs with feeding.
add HUGE and expensive amounts of beneficial bacteria every few days for the rest of your life (maybe buy stock in their company?)
perform the entire drain/clean/pressure wash process at least once a year, twice if you have many fish or provide them supplemental food at all.
Myths about Rock Bottom Ponds
They say the rocks protect the liner from the sun's harmful UV rays. 1.5mm of water also protects it from the UV and the product is UV-stabilized to last 20+ years.
They say the rocks protect the liner when you have to enter the pond and walk around. Yeah Right! Two things wrong with that picture… I’ve yet to see them carefully go through each rock and pebble to make sure there are no sharp edges or pointed surfaces. AND…. Somehow I can’t see the improvement when compared to walking around on a thick rubber liner with rubber soled tennis shoes.
They say the rocks/gravel provide more surface area for bacterial biofiltration. Mostly Wrong. During the first few weeks, the increased surface area provided by the rocks actually does allow for more beneficial bacteria to colonize and acts as a substantial part of the filter. But as soon as the mulm and debris begins to accumulate, only anaerobic metabolism can prevail with potentially disastrous results. If their system provides MORE bacterial biofiltration, then how come you have to add dry powder bacteria for the rest of your life?
They say the rocks provide the appearance of a "natural" pond. Wrong. It may be the natural appearance of a mountain streambed.... but it's a pond, not a stream. A stream has a continuous natural water exchange, the pond doesn't. There is absolutely NOTHING about a man-made, pump driven water feature that is "natural". I’ve traveled all over the country and in several foreign places. I’ve NEVER seen a natural pond with a rock bottom… except a few places where it wasn’t really a pond, it was an over-flowing spring or a wide-deep spot in a year-round creek. If the dirt/debris isn’t washed out, it’ll cover all those pretty rocks and bury them, even in nature.
The say you don't need a UV light to control algae and it'll kill the beneficial bacteria. Wrong. They want you to buy their beneficial bacteria every week for the rest of your life. And UV lights ONLY affect the algae and bacteria which passes through the light, and that ain't the beneficial bacteria in your pond/filter. Now, I’ll agree that a UV light isn’t always necessary in a well designed pond, but it’s a good tool for some applications.
Conclusions: These systems "can" be made to work for you if your desire is a high-cost, high-maintenance water garden. They do NOT work as a Koi or goldfish pond.