What I did last summer (part 4): tuning the water feature

So the water was running, and everyone loved the novelty. The kids would sit out near the water feature and do school work or just play with the dogs. We added sand and gravel to the stream and watched the moving water make natural formations, such as the delta at the end of the stream. The addition of the loose sand/gravel made the stream and pond bed look natural. Meanwhile, as the sand settled it covered the bottom of the pond evenly, hiding the charcoal-covered pond bed and making it look naturally sandy.

However, the water was silty. After a day the water cleared up, but there was a silt film on the top of the pond. At the time I thought it might be something that came off the mortar -- my worst fear was that the stream was eroding the mortar. I would eventually learn that this silt was due to the sand.

On the 4th day the pump conked out. I was coincidentally outside at the time. Suddenly the waterfall stopped and water began gushing from the pump in the pond. I unplugged it and found that the plastic pump casing had broken. The casing was in two parts, held together by rigid slots that had simply broken off. I tried tying them together and restarting the pump, but at that point the motor failed to restart.

I figured the motor was probably stopped due to an internal circuit breaker (I checked the CGFI breaker on the outside outlet and the panel breaker but neither had tripped). However, I also figured it wasn't worth it to investigate as the broken casing meant I would have to take the pump back. I felt a little guilty, but I did re-read the instructions, which were very spartan, to verify that there was no warning about silty water. Lowe's refunded the whole amount.

So, back I went to the pond specialty store. I told her the problem and she assured me that the Aquascape pumps could handle the silt. She also suggested a MicroSkim to house the pump, which I bought for $280+tax. (Note: I earlier said I could not find anyone on-line who discounted Aquascape items -- today I found several sites that discount them by 15% or so. I suspect that my earlier searches were too general. Today I was searching on very precise product names. Something to pay attention to going forward.)

I had to wait 4 days before the 4000 gph Aquascape pump was available. During that time the water level in the pond was stable, indicating the liner was not leaking. however, we did lose water when the waterfall was running. Almost certainly this is due to evaporation, as the area around the waterfall is perpetually wet due to splashing. Per the literature, you can create a waterfall in a way to minimize splashing, and I'll try to do that next year when I build the rock wall at the waterfall itself.

The MicroSkim is designed to sit beside the pond, in a dugout area that may be lower than the pond depth. For now I've just put it in the center of the pond, where the box opening is really to high given the water level, but I compensate by not including the skimmer door. I plan to create a permanent dugout for the MicroSkim before this year is over on the south side of the pond.

Here is a picture of the pond on August 30, 9 days after we first turned on the water and 1 day after the new pump and MicroSkim were in place:



The black MicroSkim box sits rather obtrusively in the pond center, but it certainly works. The water at this point is now clear except for a small patch of floating silt in the center, and that would clear up before day end. I learned that I could get rid of the silt by spraying off the biofilter pads and by using a pool net to scoop it out of the pond. Once the silt was removed it doesn't come back unless you add more sand, which we have stopped doing now that we seem to have enough.

You're not supposed to spray off the biofilter pads more than once per year because you want the beneficial, algae-eating bacteria to stay on the pads. However, if you are just starting the pond spraying them off a few times to get rid of the initial silt doesn't hurt.

You can see what the pond floor looks like in the picture above, covered by sand and lose gravel. Frankly, its appearance is better than I'd hoped. Next are two pictures of the stream bed. Some of these show the under-construction footbridge and a timber that I put across the stream to aide the construction process -- I'll address that construction in the next post.





Near the top of the picture above there is a section of stream that I rebuilt during the pump outage. Some of the embedded rocks and some mortar chunks came off in a few sections where I didn't do a good job making sure the mortar was thick enough and compacted enough. One spot was right over a lining joint, and the caulking was showing through. In addition, that area of the stream was not as aesthetically appealing because the water simply rushed down a steep slope instead of meandering, and the slope was too steep to allow any loose gravel to stay put. So, I solved it all by adding a pile of concrete, not mortar, on top of it to reform that part of the stream into a "step" for the water to run over.

The concrete was something I had bought as part of building the bridge footings, and I discovered to my joy that it mixed in about 1/10th the time as mortar does. I also found, to my near horror, that the cement dye created a very different color in concrete than it does in mortar -- instead of a rusty-brown it was closer to a sharp blood red. However by covering the new concrete patch with lots of embedded stones, supplemented by loose stones, it now looks pretty cool and adds interest to the overall stream flow.

Right now the pond and waterfall are stable. I need to add water every day or two due to evaporation, because if the pond level gets too low not enough water will get into the MicroSkim for the pump. This maintenance will get easier once I get the MicroSkim into it's permanent place, because the MicroSkim door allows for more variation in pond levels. I also need to clean the debris out of the box approximately weekly.

In addition, we had one major rain storm and I found I had to syphon water out of the pond during the rainstorm to prevent a spillover and possible erosion. The MicroSkim has an outlet for overflows, so that will be automatically taken care of once it is in its permanent dugout.

We've just run into a very cold spell now, with night temps going down to freezing, so have shut off the pump. We're expecting warm weather again soon, but by end of October I plan to shut down the pump and drain the pond with a syphon until next year.

My next post will discuss the footbridge and path, which I've been working on for about a month now.