how much oxygen?

[Big Frank]

hi I have a 4ft deep 7 foot diameter pond which is equiped with multi bay filter and UV. My question is should i run the air pump, if so how often and for how long, currently I have just 2 large ghost koi and 2 small goldfish but want to add more Ghost Koi

 

[PS3]

if you are also runing a water fall that should make more oxygen
when it goes in to the pond.if you feel that you need more oxygen
just get a air pump with air stones and run the pump 24 hours/7 days a week.
but somebody else will be here and tell you more

 

[koikeepr]

Hi Big Frank. Your mind is working in the right direction. Get an air disc and put it on your pond floor. You want oxygen bubbles to come doen from the deep part, You can run it 24/7 or you can put it on a timer and run it during the day only.

Waterfalls are great, but only provide surface O2. Water is stratified into layers. The deeper your pond, the bigger those layers. The lowest layer is the one with the least oxygen, but where the fish like to hang out. That's where you want air.

Take a look at my poorly drawn pictures for what I mean.

Here are stratified layers in a pond as an illustration for you to understand them:

In the next pic, you can see what a waterfall does:

Now, you can see what oxygen does on an air hose plunged deep into the pond. Big difference:

 

[Squidhead]

You could also test for dissolved O2. There are test kits that are accurate as long as you follow the directions. A O2 meter or monitor is expensive, but really handy. Along with a bubbler at the bottom good flow in the water help keep the bubbles in the water longer and pop while under water releasing the O2. That is what you want, to dissolve it in the water so the fish can use it. Another way to tell if there is not enough O2 at the bottom is if the fish are constantly going to the upper layers looking for the O2. I don't know if this is practical for a pond, but there are submersible pumps you can get with a venturi and have special impellers that really chop up the water. These are the kind that are also used for protien skimmers that reef keepers use. The little pumps really work as more then oxygenators. You can direct them to "dead" spots in the pond to kick up debris towards you filter intake.

 

[koikeepr]

As long as you can break up the stratified layers, you are solid. A venturi would work and there are many DIY versions for ponds to help do this. Here's one, and there are many others that can be find online.

 

[philljp]

One thing Id like to know is, how deep is each of those layers? ie, if you have quite a shallow pond, around 0.5 meters, then its possible a waterfall could supply enough oxygen?

 

[koikeepr]

Think about your pond in thirds, and that is roughly how deep each layer is.

 

[philljp]

Think about your pond in thirds, and that is roughly how deep each layer is.

ok, thats fair enough. I have 4 oxiginator plants in a 250 liter pond, so hopefully thats enough. If you think otherwise, let me know

 

[koikeepr]

I'm sure you've answered this before, but what is your filtration.

Plants are not enough IMHO. Particularly in the evening when they are producing CO2. Everyone can benefit from a well placed air disc and pump.

 

[Squidhead]

ok, thats fair enough. I have 4 oxiginator plants in a 250 liter pond, so hopefully thats enough. If you think otherwise, let me know

Phil, if you want to be sure you can purchase an O2 test kit. Dangerous O2 levels are at or below 3-4ppm. reccomended is 7-10ppm. when water is at 100% O2 saturation it is somewhere around the 10ppm range. A waterfall, algae and plants should do it. If you want to add the bubbler aeration that will help too. I would guess a waterfall would be plenty. If your fish are hanging at the bottom and don't seem distressed they should be fine. If they are always at the surface area, that's an indication there could be an O2 problem.