Test to reduce pond foam

[farne230]

Ever since my GH dropped down to 4dH, foam has been accumulating on the surface of the pond. I have been using a pool net to scoop some of this out of the pond. I have decided to increase my water and filter maintenance. In the past I have cleaned and backwashed all three filters once a week and replaced 12% water (1,000 gallons). I propose to increase the frequency of filter backwashes to each day and replace 300 gallons per day of pond water or an additional 1500 gallons per week, giving me a grand total of 2500 gallon water changes (30%). I hope the foam accumulation will go away. I will monitor temp/ph/orp/gh/kh for any change from normal.

Any predictions?

Bob

[JasPR]

mmmm, that's an interesting question

A 'water change' is typically a removal of a set amount of water ( let's say 50% to make the math easier) and then the replacement with pure freshwater. So there you have a dilution factor of 1/2.
A 'top off water change' of course is not the same. The older printed literature cautions newbies to not conside this a water change at all as you are not diluting anything. That is true to a degree but it is not a useless endeavor. A top off adds back both buffering capacity and mineral content, it just doesn't cut pollutants that are already produced.

What you are doing is perhaps the most meaningful water change, that is a targeted water change where the most polluted area of the pond system is removed. The dumping of the sump, for instance, and an addition of new water is very effective as you are loosing both organics and the 'future ammonia' and ultimately the nitrate that ammonia will produce once the heterotrophic species get to it .
And since one of the byproducts of organic oxidation/reduction is DOCs, you have a very targeted water change when you remove waste from filters and free up the biofilm of excess organic build up ( a heterotrophic bacteria feeding ground).
So I'd expect that you will see less DOC on the surface. However, what is already in circulation will be very much attracted to the surface and you might have to be patient and do the routine for a while before you see results. - JR

[koibooi]

About 4 months ago I comissioned two new ponds. The one is a 14 ton pond and the other a 8 ton pond. They have exaclty the same filtration systems, UV's and air and they each have a 18 000 l/h pump. The bigger pond therefore turns the water over a little slower than the small pond. The bigger pond has a slightly heavier fish load % and heavier feeding. The water in the bigger pond stays clear all the time but the smaller pond tends to get a bit dull at times. I then stop feeding in the small pond and the water clears up again. The bigger pond is in full sun but the smaller pond is in permanent shade.

They both generate foam but the foam is different. The bigger pond generates a pure white foam with a lot of air bubbles that sometimes stand about a foot in height and is a dry type foam (pic 1). The smaller pond generates a brown/green thin layer of foam that is like a wet sludge if you scoop it off (pic2). Can one perhaps identify the type of problem by the type of foam or are all foam problems the same - DOC's?

[JasPR]

Absolutely you can. Remember, bubbles are caused by water tension. And water tension is a result of a gathering of molecules ( typically at the 'skin layer' of water where water and atmosphere meet. The reason for this is that organic molecules have a postive 'end' and a negative charged 'end' and that polarity causes them to be attracted to that surface zone where air and water meet.
As I mentioned in the other post, the other role that plays out in your ponds is the biological process known as mineralization. This is when bacteria breakdown organic material to in the process of making energy for themselves, into base molecules. This is the creation of ammonia, but other byproducts are also released and otehr bacteria attack those products. We typically think of all these biological processess as decay. And in a very biologically active system decay can happen very quickly at temperature. Aeromonas abd pseudomonas , by the way, are common associated species found in most ponds and ones that grow in number when DOCs are common ennergy sources. This is why knowing your 'foam type' is important.
You mentioned crowding. Koi release slime coat as they move thru the water column. It is what allows then to 'slip thru' the water with very little water resistance. This slime, over time, can also build in the water column. This is of course, one other organic that can cause foaming as it coats water and creates bubbles.
In addition the bad habit of adding salt to water causes excess slime coat. Sodium itself will cause bubbles and excess slime will cause bubbles. when you add aeration from an air dome or stones, you encourage the formation of foam as the rising bubbles create the same condition for foam formation that the surface of the pond does. That is, the 'zone' where postive/negative charged materials can collect. So you can think of rising bubbles as 'lint collectors/ brushes ' gathering 'organic lint' in the water as they rise.

To try and identify what you foam is, fish go by color and then by smell. Green foam is almost always algae. Dark green foam in otherwise clear water is fish waste. Yellow foam is the 'real deal' and represents DOCs ( organic dyes, fatty acid chains and amino acids and partly broken chains of protein). - JR

[farne230]

JR-In my case I am wondering the effects of using a ion exchange softener (salt) to drive down the GH. How would this effect generation of foam, (since there was not foam prior to reach about GH 5.
Bob

[JasPR]

Maybe, but in the amounts you are adding new water, I kinda doubt it. Try testing that theory though by adding water to a large contained and aerating the heck out of it. That will at least tell you something about the nature of your water. The other thing you can do if you go that far in testing is to hook up a cheap foam fractionator to that test container and compare the foamate you get from that experiment to the foam generated in the pond.

The other helpful test to better understanding your water is to let the collected foam settle over night and examine the watse water that is created by the now dissolved foam. Also do the 'smell test', it is admittedly gross but a snife speaks volumes in some cases ! JR

[farne230]

Great advise JR. I have completed one week of increased water change and filter cleaning. I went from 10% per week water change to cleaning filters every day and in the end changed out an additional 1500 gallons or totaled about 2500 for the week. I found no change to foam accumulation. I have not tried JR suggestions yet, but I am considering that next.
Bob