At my office building I have an outdoor decorative fountain. It is
concrete, painted with blue swimming pool paint. Approximately 7 1/2
ft in diameter, 18 inches deep, curving hemispheric sides. Statuary
rises in the center and a 300 gph pump elevates water about 4 ft to a
figurine pouring water from an urn. The water flows down into two
shells and then is returned internally to the pool (no splashing).
There is an overflow drain at 18 inches, and an automatic refill pump
to maintain water level.

Dark green algae grows on the side of the pool. After a while the
water turns green and gets dirty. In the past I have dumped in bleach
weekly and then swept, drained and refilled the pool monthly to
maintain a pleasing appearance with clear water. This process does
not eliminate the dark green algae, but seemed to keep it under
control.


I've had an indoor aquarium for about a year with modest success, so I
thought perhaps I could add some fish to the outdoor pond/fountain to
control the algae and add interest.


After draining, cleaning and refilling the pool I added a dozen feeder
goldfish. 3 survived. I added another 20 after a week, and had 6
left. I'm told that survival rate is not unexpected with feeders.
So, I added 3 larger (3-4 inches) goldfish. I have been feeding them
once a day about a teaspoon of floating pellets until they are
acclimated. The larger goldfish seem to be quite active and healthy;
the feeders are dying off.


I have also added 4 small (1-2 inch dia) floating plants that look
like lily pads but are not.


The dark green algae is growing more dense. Worse, the pool water now
appears a lighter green, is murky so you can hardly see the fish when
at the bottom. The water coming out of the figurine urn appears
clear, but the shells are beginning to look greenish. Still, the fish
appear active and healthy.


The pH is 7.6. I tested for ammonia and the test indicated no
meaningful amount. A pet store tested for nitrites and said that
looked ok. I have tried adding an algicide without noticeable effect.
I tried adding an indoor aquarium Clear Water solution, with no
effect.


I have an indoor algae-eater that has grown a bit large for the 20
gallon tank--should I put it in the fountain pool? Add more goldfish?


I want to maintain a healthy habitat for the fish, and still have an
attractive fountain pool. One store suggested a pond filter, but that
listed at $100 and seems a bit much for this size pool.


Thanks for your comments!


Greg

Hi Greg,
In my opinion, your algae problem has increased due to the new
"bio-load" in the pond - ie., fish poop and fish food. Adding more fish
without proper filtration will only make the problem worse!!

I would certainly not continue the use of any algaecides!!! These are
typically copper based and are toxic to most fish and plants!!!!
Frequent additions of tap water should be avoided as well, as this only
promotes algae!!


In the short term, you will have to have patience and give your
ecosystem a chance to establish itself. The installation of a good
filter/UVC might speed things up, but keep in mind that establishing a
bacterial colony within your biofilter is a 6-8 wk. process.


There are two products available that I've had tremendous success with -
both natural beneficial bacteria, non-toxic to fish and wildlife. If
you would like more info on these, contact me privately.


Cindy McCord

For low maintenance - no plants or fish, a copper chelate algicide
and/or diquat herbicide, then a dose of chlorine every couple weeks.

Or keep the fish, and add enough water hyacinths and other plants
to starve the algae. Fish add nutients to the water, and if they
aren't enough higher plants to absorb them, algae step in to fill the
gap. With enough plants, the water and statue will remain clear
and clean of algae, except during short seasonal algae blooms.
The pool bottom will become covered with a fuzz of algae. If that's
not esthetically acceptable, go with the first option.
- Rod

I do agree one must decide if one wants a clean fountain or fish pond.
Healthy fish ponds grow algae on the sides, it helps filter the water. Do
not put any more fish in, as I'm sure you're overstocked though you don't
give how many gallons the pond contains. If the pump is deep and accessible
enough how about a home-made bucket filter? Might cost ya $10. See below:


Very easy filter to make: Depending on pond & pump size take a 1/2 to 3
gallon bucket, insert pump. Get your choice of bio-media and a bag or 2 of
carbon. Bio-media can be filter matting & carbon matting that you will see
for sale as accessories for more expensive filters or you can use plastic
bits & pieces like old curlers, clean (never seen soap) kitchen scrubbies,
or Frost King furnace filters. Put this kind of stuff around the bottom of
the bucket around the pump. Then use a layer or two of filter matting or
100% polyester batting (for quilt making) top it off with some crumbled up
vinyl screening and top with a vinyl screen lid held in place by a big
rubber band. Your local hardware & craft store should carry most of this
stuff. 1st few cleanings should be just to the layers of vinyl screening.
Cleaning anything else requires just a muck out and (non-chlorinated water
rinse) as you don't want to kill the bio-bugs on the plastic or other
bio-media. I have a small 35 gallon Patio pond in my living room. (Can be
seen on my website.) I've used a smaller bucket with 3 layers of open cell
foam (the best stuff if it has large pores, mine has only 20 pores per
inch, but hard to find unless you order a large amount, but you might get
lucky if you have a pond shop in your area). Once you get things balanced
you won't have to replace the carbon till next Spring. I, personally, use
carbon until the bio-bugs are up and running in both little & big ponds.
You might want to keep a fresh bag in there just for an extra measure of
safety. Change it about once a month, then. ~ jan

My suggestion would be to use a quick clarifier. You can find a great clarifier at sunterrausa.com.. I have used their product before and find them to be a great resource.

Cindy wrote:

Hi Greg, In my opinion, your algae problem has increased due to the new "bio-load" in the pond - ie., fish poop and fish food. Adding more fish without proper filtration will only make the problem worse!! I would certainly not continue the use of any algaecides!!! These are typically copper based and are toxic to most fish and plants!!!! Frequent additions of tap water should be avoided as well, as this only promotes algae!! In the short term, you will have to have patience and give your ecosystem a chance to establish itself. The installation of a good filter/UVC might speed things up, but keep in mind that establishing a bacterial colony within your biofilter is a 6-8 wk. process. There are two products available that I've had tremendous success with - both natural beneficial bacteria, non-toxic to fish and wildlife. If you would like more info on these, contact me privately. Cindy McCord

Cindy,
Please send the name of the products.