Friday, August 3, 2018


I hadn’t thought much about having a water garden.  But with a natural pool, you get one.

Last August the plants around the new pool consisted of about 90% reeds or sedges and some pickerel weed, all striving to help filter the water in the swim part of the pool.  They were too young then to do much filtration, and water clarity was fragile. It was a brand new ecosystem.  Without the weekly addition of algae-eating bacteria the water would have gotten a greenish cast and there could be surface gunk too. It was necessary to add algae-eating bacteria to help control nutrients in the pond water, thereby depriving the algae of food.  The bacteria also act to transform some of the dissolved nitrogen compounds that could become algae food into nitrogen gas that diffuses into the air.  A weekly cup or two of added bacteria did the trick.  (None of the chemicals used to clarify normal swimming pools can be used in a natural pool.)

August, right after completion

The sedges and reeds were nice, but not particularly exciting.  Then in midsummer pool builder Tim Lindemyer added some robust plants to fill empty spots: water lilies, irises and dwarf cattails to replace or add to the pickerel weed that was growing far too meekly.  With the echinacea in full bloom by this time and the grasses now mature, both serving as backdrop to the water plants, an attractive layered harmony has emerged. 

August 2018. Skimmer and algae grabber in the foreground.

A modest (or maybe not so modest) variety of creatures live here, but not fish.  Fish would only complicate the already dynamic ecology, adding nutrients instead of removing them, especially if they were to multiply. But there are newts, some tadpoles, the usual pond bugs, and frogs.  They found their own way here.  A garter snake was spotted one day last month, swimming!  In July we often found the larval shells of dragonflies. The dragonflies may have been born from eggs laid in the water.  Probably some of the frogs, too..

There hasn’t been a glimmer of surface algae growth this summer, nor the slightest greenish cast to the swim water.  None of that. However.  This summer’s bane has been hairy algae, a completely different type of algae, one that likes to cling to the bottom of the pool, attaching itself to stones.  It is amazing stuff.  Completely benign, happily, it has the capacity to double in volume in a short time, unhappily.  This entails nearly daily scooping of the stuff.  I pull out what I can (some portion inevitably refuses to give up its grip and prepares to regrow in the same place) and toss it in the field. I leave much of it as-is in the plant area because frogs seem to enjoy sitting in the midst of it.  Besides serving as cover for frogs, It should be good for something.  But what?  Could its presence have discouraged the other form of algae, that surface stuff?  Could the two varieties have been vying for favor?

A blue of hairy algae covering some stones 8 feet underwater

A sample of hairy algae out of the water. "Hairy" is not a misnomer.

There are many ways to get rid of hairy algae.  One suggestion I came across advised encouraging your children to pull it out.  Fun.  I can see that, kids tossing the stuff around, putting it on somebody's hair, etc.  Seriously, though, pulling it out with a stick is pretty effective. I have a telescoping pole with a paint roller holder attached to the end.  Even better, though, is donning my mask and snorkel and getting to work on it with my hands.  The best solution may simply be not filling the pool with hard water.  Hairy algae, as anyone with a fish tank and has fought the stuff can tell you, loves a high pH. And, boy, do I have hard water.  Filled now by unsoftened well water, the pond's pH sits around 7.8, the cliff edge of okay.  I plan to fix this by rerouting a hose connection through the water softener.

Lily and lily pads in the raindrops

Will this weigh the balance in another direction?  It will be interesting to see how this little ecosystem will develop in another year or so. This fall I will trim the sedges and cattails in the plant area.  I will move the water lilies (rooted in pots) to the shallow part of the swim area to overwinter.   The filter pump will be shut down and stored. Ice will eventually cover it all.  Then I will wait.  I will forget about it.  When the pond awakens in the spring, I wonder, will it be in balance?  Will it tip this way or that?  What will be the next dynamic in this little water world?