|
My pond is a .210 gallon in ground pond
it has one large water lily. The fish are 2 koi and 6 6 inch
comets. My pumps are a 210 gallon an hour with no filtration
and a 535 gallon in a box filter . and I change the water
every 2 to 3 weeks and the water will stay clear for a bout
a week or so than it goes back to being pea soup green. I
have read all the books I can get an it confuse me on what
type of filtration I should have What do you think I should
do I have been think of buying one of those box filters with
UV I saw in doctor fosters catalog .
Matthew
Hi, Matthew,
Well, there's good news and bad news here. While your filtration
exceeds your fish load at the moment, your koi will grow rapidly,
and will, within the next couple of years, begin to stress your
system. That's the bad news.
The good news is the green water! Your filter is generating
large quantities of nitrate from the ammonia that your fish
are producing, and that is pure plant fertilizer. The water
lily, while a greedy feeder, is not able to keep up and the
excess nitrate is feeding the floating algae. Left alone, the
algae will generate oxygen during the day, but at night will
suck up all the available oxygen in your pond, and when thick
enough, can smother your fish.
You've kept this controlled with water changes, but the kind
of changes you describe (I'm assuming you are doing close to
100% per change) are stressful both for your fish and your filter,
especially if you are using chlorinated tap water without a
dechlor treatment like Amquel. Straight from the tap, a 50%
water change has enough dissolved chlorine and chlorine to kill
off your biofilter and damage your fish's gills. The delay in
your pond's color change may well be caused by your filter's
biosystem ramping back up from the damage.
If you are doing any water change larger than about 5%, you
need to pretreat to remove chlorine and chloramine after you
drain and before you refill.
Many experienced hobbyists deal with some of their algae problems
with verge plantings of marginal plants such as water mint,
reeds, cattails, pennywort and other hardy perennials. Your
pond sounds a little small for this to be a successful strategy.
In your case, a UV system is the best answer. Many of the newer
box filters with built-in UV are elegant and cost-effective.
Your "pea soup" pond will be a thing of the past. It may not
be the end of your troubles, though. Your small volume and large
filter will chew up the natural buffers in your water at a rapid
rate, dropping your alkalinity to the point where your pond's
pH may become unstable. Small ponds are also prone to rapid
shifts in temperature through the day, which can stress the
fish. Plan to invest in a really good test kit containing reagents
for pH, alkalinity, chlorine, chloramine, ammonia, nitrite and
salt. Dissolved oxygen is a good thing to measure too, but the
tests are cumbersome and expensive, and the meters require an
expert to calibrate and run.
You might also consider enlarging and deepening your pond, especially
if you are interested in koi keeping.
Bob Passovoy
President
MPKS
|
