Floating scum battle

[PAwrangler08]

Hello all!!! New here!!! I have a traingular (for what its worth) pond that is roughly 300gal. The pond was here when I bought the house. I have 12 koi that are roughly 8" each in the pond. I have kept aquariums, fresh and saltwater, for the last 15 years. Currently in the pond I have floating algae. Not only is it floating on the top, but it is also floating in the water column, and along the bottom. It isn't anything like hair algae or anything like that. I have some pictures attached. I have tried skimming the pond and I have been thinking about getting a Tetra Pond bio active pressure filter for up to a 1500g pond. Currently the previous owners had an off brand pump going to a Tetra waterfall filter which has 2 pads and a big bio bag with lava rock in it. The water, as you can see in the pictures, is so cloudy that I can't see the fish most of the time. I do see them near the water fall at times which makes me believe that they are looking for oxygen, which doesn't surprise me with the amount of algae in the water. I have not fed the pond at all yet this year, while the water is probably approaching 70 F. I'm in Pennsylvania and we have been having quite a bit of rain lately, I'm not sure if that is a contributing factor or not. The pond is in the corner between my garage and a fence, so it in the shade most of the day. I just tested the water with an API test which is as follows:
pH 8.4....this seems extremely high for FW in my opinion.
Ammonia was less than .25 but not quite yellow for it to be 0
nitrite is 0
nitrate is 0
KH is 6
GH is 1
Po3 is 0...which i'm assuming is because the algae is eating it all up.

Here is water the water looks like

Now to me with the ammonia being as low as it is and the nitrite/nitrate being where it is means one of two things to me. Either it's in a cycle for what ever reason, OR there is such a small amount of ammonia and the reason for such low nitrates is because of all the rain we have had lately? Now all the algae has only been progressing for the last couple of weeks when it started getting warm out. During the winter the water was crystal clear.

So do I get the TetraPond pressure filter and hope it pulls out all the algae? Or what do I do at this point? I have not added any water via garden hose. I have not done any water changes, and to be honest, I don't plan on doing any water changes to a pond....

The plants seem to be thriving, especially the pads.

Any help is greatly appreciated!!!

Thanks!

-Blair

 

[MitchM]

I hate to tell you this, but the first thing you should do is re-home all those koi and replace them with no more than 6 much smaller goldfish.
You'll have ongoing excess nutrient problems if you try and maintain those koi in a healthy state within that size of pond.
For now I would scoop out as much built up detritus as you can and hook up that Tetra pressure filter you mentioned.

 

[PAwrangler08]

I'm only guessing it is 300gal. pond. It is 7ft by 12ft and goes from 1ft deep to about 3 ft deep.

 

[Mmathis]

Your pH is fine. Your other values look fine, but yes, the ammonia is probably a tad high. For a 300 gal pond, you have way too many fish, especially if they are koi -- your biological system is barely keeping up with the excess nutrients in the water, which is the cause of the algae. I would re-home as many of those koi as you can; add more plants [if the fish don't bother them]; add air via an airstone and air pump. You can try a different pump/filter, but until you correct the problem [too many fish], you're still going to be in the same situation.

Now, my math skills are not the best, but just looking at your pond -- it looks like it holds more than 300 gallons. But even if it is larger, the "rule of thumb" is something like 1000 gallons for the 1st koi.....and that's as far as I know the rule......I have goldfish, so don't commit the koi stuff to memory.

 

[mrsclem]

With the dimensions you gave , your pond is probably close to 1200 gallons. Still too small for more than a couple of koi.

 

[sissy]

koi grow fast and you have the waterfall thing why not add some lava rock to it and make it work .Pressure filters don't do much

 

[Meyer Jordan]

Get the pressure filter but continue to utilize the waterfall filter also. Considering that size (1200 gallons) pond with that many Koi you are grossly lacking in biofiltration capacity.
The reason that the Ammonia level is as low as it is is because all of the algae is feeding on it in addition to the Nitrate and the Phosphous. through assimilation. What you really have is an algae farm.
I would place a priority on re-homing a few of these Koi while increasing the biofiltration.

 

[budgenator]

MitchM, Mmathis and Meyer Jordan all gave good advice, I would add, you're probably going to have to do a few 10 -20% water changes as well, You've kept aquariums, you know the drill. Besides pond water is the best stuff for watering your flower garden.

 

[CometKeith]

Hi Welcome!! Agreed with all the comments from above. If you follow their advice you will be gaining from years of learning and wisdom. The algae is not the problem it's the symptom. It will go away on it's own once you have the pond properly balanced. Right now the bio-load is way too high.