Recent Questions
     Water Quality & Filtration

Q. Hi,

The water in our pond is showing a high PH level. We have successfully added PH lowering stuff to bring it down. However, it is back up again. What causes the PH to climb?

Karen Martin

A. Hello Karen,

High pH is a relative thing. Let me explain.

If you are only keeping plants, I wouldn't worry about the pH level at all. If however, you want to keep fish in your pond, they tend to like it a little of the high side. A pH reading of 7.0 to 8.5 is actually ideal for keeping Koi. What all fish cannot tolerate are rapid swings in the pH level. An upswing in the pH level is not a real concern unless the pH levels reach 9.0, at which pint we recommend a 25% water change. Anything above 10.0 - immediately evacuate your pond of all fish life until you get the problem under control. Even more concerning is a rapid descent in the pH level or a crash.

A properly built pond constructed using rocks & gravel, a biological filter, fish, plants and beneficial bacteria will naturally balance itself out in the end. Emulate Mother Nature and she will keep your pond in balance for you.

If you're concerned or stumped, our store staff sell different buffering agents to help stabilize you pond. They are primarily used to get you our of a pH pickle and should not be used on a continual basis.

Q. Hi,

My pond has a lot of white bubbles mostly in the morning at the
bottom of the waterfall.  I can remove some of them with the net but they break up and go all over the pond.  I'm not sure what to do. Can you give me some idea what it is and how to control it? 
Thanks

Mary Boudreau

A. This is usually caused by pollen getting into the water. The bubbles are harmless to aquatic life and will eventually go away, but I fully understand why pond owners want it gone sooner than later. I've seen a couple of ponds look like someone's poured a cup of Mr. Bubble in the deep end. Foam & bubbles can be controlled organically with a product called EcoFoam Away. Drop by our retail store. They keep the product in stock.

Q. Hi,

What is the best way to get ride of string algae

Clair Fleming

A. String algae in your pond are Chlorophyta, a division of green algae which includes about 7000 species of mostly aquatic photosynthetic eukaryotic organisms. They contain chlorophylls, and store food as starch in their plastids. The most common form sting algae in a pond is Spirogyra (not to be confused with the now long forgotten 80s big hair band). It is made up of  long chains of individual rectangular cells links together by cellulose & pectin. It cannot be controlled using flow-through filtration because it tends to attach itself to rocks, gravel & other plant material in a pond. It can be pulverized biochemically by using various oxidizing agents to break apart the cellular links, allowing the suspended debris to be trapped in the filtration system where it can be digested by beneficial bacteria.

The Pond Clinic suggests two methods of control for string algae:

1) Post-Emergent Control - use Aquascape EcoBlast & S.A.B. to break apart existing algae, both of which are safe for all fish and other aquatic life forms.

2) Prevention - use Aquascape EcoBarley (again safe for other aquatic life forms) which slowly releases peroxide into the pond acting as a prophylactic against the onset of algae growth.

We recommend that both control & prevention methods be used for maximum effectiveness.

The Pond Clinic carries the entire line of Aquascape products. Feel free to speak with our retail store staff for proper product use.

Q. Hi,

What is the cheapest way to get rid of green sludge

Marc B

A. It depends on what you refer to as "sludge".

If you are referring to the mucky debris that accumulates on the bottom of the pond, you're best to get the water moving and oxygenated, then add a sludge digesting bacteria like AquaClearer Sludge Cleaner. This will help break down the sludge and convert it into nitrate which can then be absorbed by the plants in your pond.

If you are referring to stringy green filaments and blobs that attach to the rocks and create a scum on the surface of the water and/or a fuzz on the rocks and gravel in your pond, that's string algae and it requires a slightly different approach.

String algae cannot be filtered out of a pond because it attaches itself to things and cannot be swept into a skimmer filter and into a biological filter where it can be broken down by beneficial bacteria. You must first break it into little bits. To do this we recommend you add an oxidizing agent like EcoBlast or S.A.B. which immediately release natural peroxides, breaking down the links between individual cells which make up a string algae filament. The debris is then swept into the filtration system and biochemically broken down into nitrate (fertilizer for your aquatic plants) just as Mother Nature does every day. To prevent it from reoccurring, add EcoBarley Extract which acts as a prophylactic by slowly releasing organic peroxides over time.

Your pond and its filtration system are nothing more than a huge, pretty aquatic compost bin. Given the right balance, Mother Nature will clean up your pond for you.

Q. Hi,

I wrote to you earlier in the season. I had a terrible case of string algae. Since your reply, I completely cleaned the pond, paying special attention to getting it as clean as I could (I've been to one of
your seminars on the topic). I believe that there were too many nutrients in the water, causing the algae, so I made special efforts to get things really clean. I even partially filled it, playing water down all the sides, and re-emptied it, to get remains of organic matter.

I cleaned the biofalls, pressure washing the pads and those plastic ball thingies. I put in a heavy dose of Pond-Zyme plus.

Two weeks after cleaning, I have the makings of another terrible infestation of string algae. I have added NO nutrients (such as by feeding the fish).

Help! Why is this happening? How can the recently-clean water support such heavy growth? Where are the nutrients coming from?

Thank you,

Ian

A. If your plant material is not fully emerged yet, ANY nutrients in the pond will be absorbed by algae because it is the fastest growing plant in the pond. Also, the nitrification cycle takes 4-6 weeks to completion, so keep adding Aquaclearer bacteria to the pond daily for the next two weeks to seed the filter. Then add it every week according to package directions. To control algae which has already emerged, use EcoBlast and S.A.B. in combination. Both are oxidizing agents which break the algae away from the rock and gravel and emulsify it so it can then be swept into the skimmer and
biological filter where the beneficial bacteria can digest it. To prevent the algae from reoccurring apply EcoBarley weekly which releases a slow dose of organic peroxide which limits the growth of new string algae. Throughout all this, DO NOT clean your biological filter or you will destroy your bacteria culture and have to start the process all over again.

Q. Hi,

I'm a customer and have attended several of your seminars. Last summer, a very stringy type of vegetation (algae?) started growing in the pond for the first time. It takes over the pond in great stringy mats throughout the water (not usually on the surface). I have removed vast quantities, but it is still there this spring. Can I eradicate it? (I wonder if last summer's rains washed too many nutrients into the water, or if a new organism has taken hold and will never go away now.) Thanks. Ian

A. Dear Ian!

The green 'stringy' stuff growing in your pond is called string algae (Latin name: Spyro Gyra). It is usually caused by a nutrient imbalance in the water. When death and waste accumulates in your pond, it is broken down into ammonia. Since ammonia is toxic to fish, naturally occurring bacteria called nitrosomonas break down the ammonia into nitrite. It too is toxic to fish, so another type of bacteria called nitrobacter break down the nitrite into nitrate. This process is called the nitrification cycle. Nitrate is essential fertilizer for green plants. If you do not have enough plants in the pond to absorb the free available nitrate, then the algae will begin to grow as it is the lowest common denominator in a pond.

My advice would be to speak with our retail store staff to see if you have the right balance of plants (and fish). Also, if you have a properly working filtration system, you can add beneficial bacteria to help break down the debris quicker.

Finally, as a prophylactic measure, you can add a barley extract to the pond. As the extract breaks down, it slowly releases natural peroxide which lyses the cell wall of the string algae plants, breaking them into little pieces. The debris is then drawn into your filter where the beneficial bacteria can digest it through the nitrification cycle.

It's all about balance. If all the components in your pond are in balance (bacteria, plants, fish, circulation, aeration & filtration) then Mother Nature will clean your pond for you.

Q. Dear Pond Doctor,

Does a backyard pond mean I will have a lot of mosquitoes?

A. Mosquitoes only lay their eggs in stagnant pools of water.  The water in a well designed pond is constantly moving so mosquitoes are rarely a problem.  If the blood-thirsty devils do happen to lay eggs in your pond, and they somehow manage to hatch, your fish will help themselves to a delectable treat and pick them off in short order. Any leftovers will be swept away into your skimmer filter.

Q. Hello Pond Doctor,

I want to build a bigger pond this summer, but I am worried that it will just mean more work to maintain it. What's your opinion?

A. The truth is that the larger the water feature, the easier they become to maintain.  Any aquarium hobbyist will tell you that larger fish tanks are easier to maintain because the ecosystem you create becomes more stable as the volume of water increases.  Water will heat and cool more slowly, and nutrient levels will stay in balance. Also, bigger ponds have large areas of open water, which does not require mowing, weeding or watering.

Q. Hey Doc!

I have a 14' x 19' pond with a waterfall and stream, with a BIOFalls and Skimmer filter.  A friend told me that I would be better off using a UV filter to control algae. Is this true?

A. While UV (ultra-violet) clarifiers do help keep pond water clear, there are several drawbacks worth considering.  First, no matter how intense, UV clarifiers only break down suspended algae and do not break down string algae which can become quite unsightly. Second, after the suspended algae are killed, the dead debris falls to the bottom of the pond, biodegrades and provides fertilizer for the next, often larger, algae bloom.  Third, UV systems are quite expensive and require replacement bulbs every spring.

The fact of the matter is that if you have a pond which is naturally balanced, the fish eat the plants, and then produce waste that gets digested by aerobic bacteria colonizing on the rocks and gravel on the bottom, which gets taken up as nutrition by aquatic plants continuing the cycle of life.  A naturally balanced pond with proper aeration and mechanical filtration is a low-maintenance pond because Mother Nature is doing the cleaning work for you.  After all, Mothers are very good at getting small creatures to pick up after themselves.