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Getting Rid of Algae and Clearing Water


I get asked at least 5 times a day in the summer the dreaded “Why is my water Green?” or “How do I get rid of Algae?” questions. If you ask 10 different Pond Experts you will get at least 15 different answers. After years of Ponding, I have found the following to be the Keys to a clear, algae-free pond.    

What is Algae                              

There’s typically 3 different types of algae that many of us may be plagued with.  The first kind is ”green water’ algae.  It is simply a microscopic plant that makes your water look green.  The next kind is string algae and it typically grows on rocks, in between water lilies and other aquatic plants and looks like long green hair.  It grows on these places because the water is warmer than elsewhere in the pond (especially shallow areas around the shore or on a waterfall) and there may not be as much water movement . Many of us get frustrated and just pull out the string algae by handfuls but what you’re actually doing is making the problem worse.  String algae releases millions of tiny spores throughout the pond when it’s pulled out thereby creating more string algae plants to grow.  So, it becomes an on-going situation.  It’s best to cut the string algae with a pair of scissors if you are going to manually remove it.  In addition to ‘green water’ algae (planktonic algae) and string algae, there’s also filamentous algae which looks quite disgusting.  It looks like green throw up or something and floats on top of your pond.                              

1.  Filtration                              

The rule-of-thumb is to ensure that the water is turned at least once per hour through your filters. For a 1,000 gallon pond, you need a pump that pumps the water at least 1,000 gph at the head height that you are pumping it to. It might take a 1500 gph pump to pump 1000 gph water 4 feet vertically and 20 feet horizontally. This is the 1st step toward water clarity. Clear water can be achieved with a variety of filters including Skimmers and BioFalls, Pressure Filters, Gravity-fed filters, Submersible Filters, etc. For purposes of this discussion we will assume that our filtration system is adequate                             

2.  Aeration                              

Aeration, Aeration, Aeration! You cannot over-aerate. This is the single thing that most of us fail to provide adequately for our ponds especially in the hot summer. The rate of metabolism doubles for every 18 degree change. In other words, a temperature increase from 70 degrees to 88 degrees, doubles the requirements of fish, bio-filtration bacteria, algae, etc.  for nutrients, oxygen and everything else.                            

The aquatic submerged plants like algae in your pond are both beneficial and detrimental to oxygen levels. During the day aquatic plants such as algae in your pond produce oxygen. However at night, they consume oxygen and compete with the fish and filter bacteria for the limited supply of oxygen in the water. This is why fish die-offs occur in the early morning hours. The lack of adequate aeration is one of the biggest factors in a cloudy algae-filled pond. Most of us have too many fish and too little aeration!                              

Large ponds and golf course lakes avoid algae problems without filtration simply by using either  large submerged aerators                      

Aquascape AirPro Diffuser


or large Fountains spraying water high in the air to aerate the pond.                            

Scott Aerator Clover Big Shot


For our backyard ponds under 1500 gallons, Aquascape’s 4-stone Aerator is a great choice.           





For larger ponds, the PondMaster Aerator  series are a great choice                        







3.  Plants             

The use of plants cannot be over-emphasized. The plants provide shade for the pond which limits the algae and also compete with the algae for nutrients                              

A good rule of thumb is to cover 30% of your surface with plants and also another 40% plants with ledges above your pond, but still where it’s in the water. It’s best to plant directly in the gravel except for Reeds, which should be kept in containers .                              

4.  Shade     

The more shade the better as the direct sun really causes the algae to thrive.                             

5.  Beneficial Bacteria     

In order to jump-start and help maintain the whole eco-system, it’s very important to use a beneficial bacteria like Beneficial Bacteria – Dry by Aquascape .   The Beneficial Bacteria competes with the algae for the nutrients and is what helps keep the water clear with a “polished” look. For new ponds or after winter, treat daily for the first 10 days with 1 scoop (teaspoon) per every 1,000 gallons. After the pond has matured use a maintenance dose of 1 scoop per 1000 gallons weekly. This can be applied by simply dropping the bacteria directly in front of the skimmer or filter which will suck the Beneficial Bacteria through all the biological filters.                          







OK – You have done all of the above and still have green water or String Algae. From here, you have two alternatives, Use Algae Treatments in your pond and/or use a traditional UV Light or the revolutionary new IonGen from Aquascape. Below are your final options:        

6.  Algae Water Treatments                              

My two favorites are AlgaeFix by PondCare (Liquid) and EcoBlast (Granules).       

The Beneficial Bacteria mentioned above can and should be used in conjunction with these products.                              

The Algae bloom begins before the rest of the eco-system has started in the spring. For that reason, it’s VERY important to use either of these products EVERY 3 Days for 2 – 3 weeks in order to “nip the algae in the bud”. If you just use these products sporadically, you are wasting your money.                              

 AlgaeFix by PondCare (Liquid): Use 8 oz for every 2,400 gallons. Mix in a bucket of POND WATER and spread around the inside edges of the pond. Repeat every three days for 2 – 3 weeks and then once a week for the rest of the summer. The waterfalls and streams are the easiest. Just turn off your pumps for an hour or two, and broadcast-spread the granules on the stream and waterfall where the string algae is. Allow to dry.                             

EcoBlast (Granules): Use 4.4 oz for every 1,000 gallons. Mix in a bucket of POND WATER and spread around the inside edges of the pond. Repeat every three days for 2 – 3 weeks and then once a week for the rest of the summer. The waterfalls and streams are the easiest. Just turn off your pumps for an hour or two, and broadcast-spread the granules on the stream and waterfall where the string algae is. Allow to dry.                             

Make sure you remove as much of the dead algae as possible or use SAB Stream and Pond Clean by Aquascape to break down the dead algae and convert it into beneficial bacteria or the dead algae will be a breeding ground for more algae.                             

7.  UV Lights                             

These are very controversial in the pond world. Many Koi people are big fans of UV lights to control green water algae and swear by them. Many UV opponents argue that UV kills all the bad stuff including green water algae but also kills beneficial bacteria as well.  Most everyone agrees that UV lights have little or no effect on string algae as the string algae never passes through the UV lights. Personally I am not a fan of UV lights either as they are expensive to operate requiring 20, 40, 60 or even 80 watts of power to operate, the bulbs need to be replaced every 9 months to a year and I prefer the more natural eco-system well-balanced pond concept.                             

8.  IonGen – Revolutionary New Product from Aquascape to get rid of Algae                             

Aquascape introduced the new IonGen Electronic Clarifier  on September 1st of last year. I was so excited that I had mine installed in my 6,000 gallon pond by Sep 6th. It took me about 15 minutes to install it. I love it!                             

The IonGen drastically reduces pond maintenance and provides crystal clear water without the use of chemicals and completely eliminates the need for Algaecides. A microprocessor inside the IonGen control panel causes the outermost atoms of copper, silver, and zinc to lose an electron, creating a positive ion. The positive ion attempts to flow from one of the Probe’s bars to the other and is swept away by the flow of water where the ion can begin to treat the water. The IonGen Probe is self cleaning, using reverse polarity to prevent scale and debris build-up on the Probe’s bars. One IonGen unit is sufficient for up to a 25,000 gallon pond.                             

Aquascape has been testing it for three years and gave it to a number of their employees to test last summer. Everyone that I talked to was blown away. They say that you no longer need to use algaecides to control the algae but you will still have to use the Beneficial Bacteria – Dry (or the Liquid or Cold-Weather Bacteria). The probes should last about 1 year. A red light on the control panel comes on when the probe is used up.                             

They emphasize that this is very different from a UV light that “fries” all the bacteria – good and bad. The IonGen only takes about 1 watt to drive the electronic control panel unlike a UV which can require as many as 80 watts.                             

Scott Rhodes, Director of Product Marketing for Aquascape, Inc, assured me that their is no impact whatsoever to the fish. They have done a number of dissections on fish that have been exposed to the IonGen and show no traces of copper, zinc or silver.                             

Please take 10% off the already discounted price on our site by using the Coupon Code – blog10 – in the Coupon Code box at Check-out.                             


date Posted on: Saturday, March 6th, 2010 at 4:21 am
Category Pond Tips.
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16 Responses to “Getting Rid of Algae and Clearing Water”

  1. John Bushmire

    We were intriqued by your Ion Gen Electronic Clarifier. We have a 6000 gallon pond with fish/plants that we built 3 years ago. We have a working skimmer/biofilter/waterfall but this past year we have trouble with algae and and the water being dark green. When we first had our pond, we had the “algae green bloom” which cleared on its own when the pond settled in after a week. Can you tell us something more about this system and also your suggestion of the benefical bacteria that will need to be used.

    March 21st, 2010 at 5:51 pm
  2. John Bushmire

    Awaiting response

    March 23rd, 2010 at 5:12 pm
  3. PondMeister

    Hi John – Whoops missed your question here. I have a 6000 gallon pond which 4 yrs ago I had string algae that I could “harvest” once a year. The last couple years I solved the problem using Algaefix by Pondcare evry 3 days for 3 weeks in the spring and then once a week thereafter. At the same time in the spring I put in Beneficial Bacteria – Dry from Aquascape every time I used AlgaeFix and then twice a week after that. That worked well the last 3 years. On Sept 6th of last year I installed the IonGen here in Sunny Los Angeles. I have not used one drop of AlgaeFix but as I was told, I continued to use the Beneficial Bacteria – Dry from Aquascape mentioned above about 2 times a week (I used the Cold Water Beneficial Bacteria from Aquascapewhen the water temperature was between 45 and 55 degrees.) In 6 months now, my water is sparkling and not one trace of green water or string algae…yeaaaa!

    March 23rd, 2010 at 9:37 pm
  4. PondMeister

    It was such a good question that I used it for a Pond Blog on our site at http://www.thepondoutlet.com/pondblog/?p=531. The Blog automatically feeds into our Facebook Wall which has over 3,000 fans.
    Hope this helps!

    March 24th, 2010 at 12:16 am
  5. John Bushmire

    Thanks for all your helpful information, we are looking forward to trying the ION Gen Electronic Clarifier with your suggestions.

    March 25th, 2010 at 7:55 pm
  6. Tina LeBouthiller

    Should the Iongen be installed in the pond when the water is clear, to keep it clear in the future? Or can it be installed when the water is green? If it’s installed when the water is green, how long (on average) will it take to clarify the pond (1,000 to 1,200 gal.)? Thanks!

    March 30th, 2010 at 5:33 pm
  7. PondMeister

    Aquascape recommends starting fresh with the IonGen with a clean pond. It will eventually eradicate the algae. I put mine in late in the season last year and gave it a couple of treratments of EcoBlast to help it along. Works great!

    April 3rd, 2010 at 9:28 am
  8. Teresa Harper

    Cleaned the pond of terrible algae earlier this Spring. Bought an IonGen from the Pond Outlet and installed it last Monday when the algae was just beginning again. The algae is barely visible, the water is clear and the fish are just fine. I’m thrilled with the IonGen and its results!

    April 24th, 2010 at 10:56 am
  9. PondMeister

    Thanks Teresa – Same thing happened in my pond!

    April 25th, 2010 at 10:04 pm
  10. John Bushmire

    We purchased the ION Gen this spring. Our pond is 6000 gal, we haven’t had any algae but our water is still green. We tried your suggestion with the chemicals also. Help!

    June 3rd, 2010 at 9:11 pm
  11. Devon Groene

    Concerning this topic, it is not so easy to find good suggestions on the Web. Thanks for sharing your ideas on natural health and related topics. So, do you have any good recommendations on where I can search for more useful suggestions on the Internet? Keep up the excellent work!

    October 23rd, 2010 at 1:19 pm
  12. PondMeister

    Thanks Devon – check out our main Blog on Winterizing at http://www.thepondoutlet.com/pondblog/?p=267. Please call us at 805-241-0141 with any other questions.

    October 23rd, 2010 at 8:06 pm
  13. Lee Dichter

    My pond is approx. 2500 gals. Year after year I get this blackish green “stuff” on the bottom that floats to the top in warm temps. and clogs my skimmer pad which has to be cleaned at least twice/day. What is this stuff and how do I get rid of it? I’ve tried many things, but nothing works. I have to resort to spend countless hours scooping it out by hand, only to find more there the next day. I know it’s not string algae. Even the fish won’t eat it! Thanks.

    May 28th, 2011 at 3:08 am
  14. John Burns

    I have two ponds with a total of 2900 and 1800 gallons of water. Every year i have String algae all over and nothing seems to works. Do you have something that will get rid of it for once and for all?

    April 1st, 2012 at 2:56 pm
  15. bernadette

    do you sell 29004 signature series skimmer 6.0 and 8.0 filter. I have a aquasurge 5000 pump. do you sell or have a supplier in london ontario canada
    thank you

    May 2nd, 2013 at 3:05 am
  16. kerry simpson

    I have a green water problem it looks like liquid cowpoo pond size 2500 gals will your iron thing solve the problem cost and where can it be purchased from in Australia kerry

    April 25th, 2014 at 2:43 am