Strange foam fractionator behavior

[gello22]

I decided to build a foam fractionator to remove more nutrients from the pond. My system is about 1800 gallons, about 10 2" minnows and about a thousand tiny pond snails. I added a second pump a few weeks back so with head loss I have about 3200gph running over the falls and 4000gph circulating through the stream.

I finished the build this evening right before it started to rain. I have read others post they get more foam when it rains, but mine seams a little ridiculous. The foam was very wet and streaming out. I increased the foam outlet to the same height as the inlet so it is now about 5 feet high and foam is still coming out at that height. As I added height the foam has started to pick up some color.

Anyone else have problems with very wet foam and this much of it. I would take a picture, but it is still raining. A sketch of my foam fractionator below.

 

[JohnHuff]

Thanks for sharing. I built one which didn't work. I found that I needed a ball valve at the bottom in order to adjust/control the height that the foam was coming out at. Would love to see pics!

 

[Waterbug]

pH has a big effect on foam in several ways. Rain being in the 5 to 2 pH range can have a big effect on ponds with low KH, or poor buffers. What's pH and KH look like?

I've never seen scheme of making the riser taller. What is the purpose?

 

[slakker]

Even feeding, etc. affects foam production... in a reef tank, you notice it most prominently as once even some food proteins hit the water, the foam production is pretty much gone for an hour or so... very finicky devices..

 

[gello22]

wb,

I'm not sure what the ph was last night, but it is running about 7 right now. I have never taken a kh reading. I do have oyster shells in the skimmer and waterfall pool. I am using a rain barrel that draws from about 800sqft of roof which I am rethinking based on the fact that a 2" rain will just about exchange the whole pond and all the bird poop that washed in.

The riser height is very strange. I started with a normal height of a few inches making it about 4" above the water level. The problem I ran into was the foam was too wet and coming out very fast. I didn't take any measurements, but in less than 10 seconds I could fill my cupped hands with water from the popped bubbles. I kept extending the riser until I had a puff of foam every couple of seconds. With the taller riser the foam is much drier and has some color to it.

The pictures below are from today I took one extension off as the foam slowed down, now it is about 4' tall. The other picture is with a normal height riser it is a continues stream of nearly clear very wet bubbles.

 

[Waterbug]

Curious where you learned about changing the riser height to change bubble type. That's pretty advanced stuff.

I like simple, so I don't see a problem with the wet bubbles, which is why I was curious about the riser height. To me the faster the bubble are removed from the water the better. The cost of losing some water is cheap. The higher riser will condense hydrophobic particles, but I assume (don't know) that some will fall back into the water stream and not be removed. Could be a lot of them, don't know. I'd be concerned that I was paying to pump this water up and not reducing DOCs as much as I could. Maybe we're talking pennies, but that's how I look at filters.

Did you know about the pH of rain being 5-2? For MN you'd be around 5.4 for normal rain. Being in a city could drop that to 4's. Rain from a thunderstorm can be down around 2. That's a double whammy, lots of rain and 2 pH.

If I followed correctly the 800 sf of roof going into the pond would want me to test KH asap. Bird crap and dirt from the roof might even be saving you, could be making things worst, don't know. Rain water is great imo if you manage the dirt and KH.

Oyster shells are a pH buffer, but a pretty poor pH buffer because they are so slow to dissolve. Crushed is better, but still not good imo. This is most true in the case of rain and even more so in your case of extra rain water is getting into the pond. If you're really exchanging a pond's worth of rain water, I don't know how long a few oyster shells are going to take to bring pH back. Hours? Days? Weeks? In the mean time you have crashed pH.

A dissolved buffer like baking soda reacts very fast to stop a crash from happening.

I've seen oyster shells used in a few in high end Koi ponds, but we're talking about multiple 100 lb sacks. And even then they're not using them as primary buffering.

So my guess is the differences you're seeing in foam type is indeed related to pH changes. But just a guess.

 

[Waterbug]

'm not sure what the ph was last night, but it is running about 7 right now.

Forgot about this...7 pH range for morning is great if you're keeping it that range on purpose or that's just where your water supply puts you in a stable way. Without testing KH and the rain deal, I'd guess 7 pH probably means KH is below 100 ppm, maybe 40-60 range. But I couldn't guess if the 7 is recovering from a crash, or going down, or stable.

 

[gello22]

Evidently I must have had an abundance of DOC after a few days I was down to a 6" riser now down to a 3" riser to get some foam to come out. Even after yesterdays hard rain I was able to keep the riser short.

My PH seems to be stable just above 7. My water supply is just below 7.

I am one of those odd balls that rocked the whole pond with river rock so I imagine I have some mineral content that aids with ph buffering.