The power of UV

[schildkoi]

Quote: Originally Posted by koibooi Logic tells me that if the UV's cause a die off rate that is faster than the replication rate then I will also get clear water. Also, if a filter has e.g. 400 square foot of media (2X) it will be more efficient than a filter with 200 square foot of media (X) even if the latter is turned over twice during the same time. In my instance the 30 ton pond is turned every 40 minutes. I would hate so see the current, pumps and electricity bill if I had to push that up to turning the 30 tons every 20 minutes.

Biofilm will only grow to its sustainable level based on the level on nutrients supplied AND at the rate at which it is supplied. If "X" sq ft of surface space is efficiently processing the nutrients supplied, adding me dia to a level of 2X surface space will not affect the ambient nutrient level within the pond UNLESS the turnpver rate is increased to supply the nurients faster and thus dilute the ambient nutriet levels further.

Now, if you are turning over your total volume through bio filtration every 40 minutes and you still have green water with a matured system, I suspect you have some other issues in your system.

Quote: In my case there is definately not a lack of filtration nor do I have too many fish in the pond. I have a seriously big filtration system holding 400 liters of K1 in two Nexus's as well as a trickle filter holding another 200 liters of bio-balls. The 30 ton pond only hold 15 koi with an average size of 70 centimeters. The problem was definately non-functioning UV's.

A 30 ton pond is 7920 US gallons. If you are turning this volume over every 40 minutes, that would mean that you are flowing 9266 gph. Not knowing ho9w you have all of the filters plumbed or how many pumps you have working, its hard to say if the set up is the most efficient possible but you do seem to have the capacities in filtration for what you described.

Based on the info supplied, I would see a 3 system pond? 2 bottom drains, each flowing to a Nexus at about 3000 -3500 gph apiece/ then the thrid system with the shower filter flowing the remaining 2200 to 3200 gph?

Now if ANY of these systems are on the same circuit, it would be an example fo what I was talking about in adding filtration w/o adding turn over rate through that filtreation. It wouldn't do any good to pass the water firt through a Nexus and then on to another nexus or even to the shower since the first nexus would have processed the flow rate already.

Another factor to the green water could be the source water itself. Oftentimes there are phosphates, ammonia and nitrites/nitrates in water sources.

Steve

Steve

[Beniguy]

I had a similar problem a few years ago, 80 watt UV in 3,200 gallon pond and green water. To make a long story short the GFI had tripped. Solution was to put the air pump and the UV on the same GFI. No bubbles, no UV!
Too simple.
Ed

[MikeM]

I agree with nearly all Steve has said, except the idea that there must be something wrong in the system if biofiltration alone does not result in desired clarity at a 40 minute turnover rate. When the pond is in full sun in a warm climate, nitrifiers cannot clear the water the way they can do in other climates or in shade. The efficiency of the algae in consuming ammonia before it gets to the biofilter becomes too great.

[BTW, there is a school of thought that UV usually is not strong enough to kill algae, but does disrupt the ability to replicate, resulting in clarity from non-replication over a period of several days. Doesn't really matter. Appropriately sized UV with proper flow rate will clear green water if operating right.]

[schildkoi]

Quote: Originally Posted by MikeM I agree with nearly all Steve has said, except the idea that there must be something wrong in the system if biofiltration alone does not result in desired clarity at a 40 minute turnover rate. When the pond is in full sun in a warm climate, nitrifiers cannot clear the water the way they can do in other climates or in shade. The efficiency of the algae in consuming ammonia before it gets to the biofilter becomes too great. [BTW, there is a school of thought that UV usually is not strong enough to kill algae, but does disrupt the ability to replicate, resulting in clarity from non-replication over a period of several days. Doesn't really matter. Appropriately sized UV with proper flow rate will clear green water if operating right.]

I agree Mike and am the first to say that southern climates are tougher to deal with unicellular algae. That being said and looking at stocking densities (on the low side) and the amount of filtration capacity in surface area, if there are 3 systems as I described, there shouild be more than enough surface area and feed rate (turnover) through them. If they are in series instead of parralel, then there isn't that 40 minute turnover that we think there is. Hard to tell without seeing everything though.

Steve

[JasPR]

Nope on the algae think Mike. At least as I'm reading it? If you have an established system, as you know, you have competitive exclusion as both a lateral and a vertical integration of species. You have biofilm ( bacteria) species competing with single cell algae and you have filamentous algae competing with single cell algae. As you know from your aquarium days, there is a natural succession of algal species as nutrient is removed by each species and bacteria becomes well established. This loss of the key nutrient or the loss of luxury nutrient/elements makes way for other species to take over that niche. So we see a progression from brown algae give way to green carpet algae and that giving way to less desirable forms. Carpet greens are very sensitive to chemicals and medications. If this important species is lost than other species come on. So unless you are seeing clear diatoms mid-day, I think Steve's comments are correct. In a system that has high oxygen, good settlement, an established biofilm and supporting algal community, green water has no possiblity of establishing itself. After all, what would sustain it? The existing species mix is highly tuned to the nutrient out put. "you make it, they take it"! JR

[koibooi]

My 30 ton pond is in fact a three system pond. The two bottom drains feed a 2 ton settlement chamber. From the settlement chamber there are two seperate 110mm feeds, each feeding its own Nexus 3000 and each Nexus has 150 liters of Kaldness. Each Nexus is fitted with an Easy and each Easy hold another 50 liters or Kaldness. That makes 400 liters of Kaldnes. The one Nexus runs a 15 000 l/h pump and the other Nexus runs a 12 000 l/h pump. From the skimmer box a 18 000 l/h pump feeds the trickle filter/shower. Top layer of shower is full of oyster shells and the next two trays are filled with 200 liters each of bio balls. I have three 55watt UV's, one on each return. The pond is three years old and in full sunlight the whole day.

I have never had problems with string algae and this is the first time I really had problems with green water algae. The only thing that has changed is that the UV's died. Once I replaced the balast on all three units, I had clear water again.

[MikeM]

The unicellular algae are always present to some degree if the water temp and light are sufficient for them to live. The population is just too low to interfere with visibility. The nitrifiers, biofilm and carpet algae will out-compete the green water algae in most conditions. I agree that it is a progression. It is my observation, however, that even the best-filtered and mature ponds cannot achieve the clarity we desire in warm climates unless either shade or UV are used. The unicellular algae reproduce too quickly when conditions are perfect. It is a question of which organism grabs the ammonia first and whether there is enough ammonia available to fuel reproduction. Have shade for part of the day from nearby trees, or an overhead cover, and the water will be clear. But in the intensity of full sun all day, in warm water the green water algae are ready to explode. Pea soup should not occur, but the murkiness is not what we desire.

Koiboii's system sounds pretty good, but it does not surprise me that he has to rely on UV to obtain clarity during a South African summer in full sun. Of course, with lower stocking the issue would not be so great. Those are fairly sizeable koi he is keeping.

[JasPR]

well, I can't really comment about Florida ponds since I never owned one nor have I really helped in a 'hands on way' like I do in the Mid Atlantic and Tri state area regions.
But I'm pretty core when it comes to tropical systems ( both freshwater and marine) and my imagine of a Florida koi pond is from that experience.
I'm always confused when Floridians tell me Florida is a tropical climate? As I had always been taught that Florida is a sub tropical temperature range added by latitude and currents. In true tropical countries you have wet and dry seasons that take the place of meaningful temperature change. Those ecosystems take a cue from changes in diet/calorie count and in teh case of water creatures/microbes the evaporation rates changing the nutrient concentrations.
So to bring that all home-- our koi ponds in seasonal America, have a shifting of biofilm membership species and a hand off to the photo synthetic groups at certain times of the year. And this pattern repeats as the seasons come and go over the years. Becoming stronger and more dependable over the years. I have not had a nitrite measurement in my pond for instance in many many many years. I have not had green water since Reagan was in office! And I think I changed my UV lights in 1996? I have no string algae, or blanket weed and only patches of red and brown algae within the green carpet algae that is only predominate on one side of the pond down to about 30 inches into the water. The bottom is seven feet and free of any algae growth. But of you touch the walls or floor ( I imagine) it is slippery and coated with a mixture of biofilm and 'tame' algal species.
The water appears crystal clear at certain times of the day and certain times of the year. For instance now, with water at 48 F, the water is like glass. But other times of the year, in mid summer for instance, at mid day, you can see some material in the water column. This is the background biology as well as non biodegradable dyes. Yet by late afternoon it is gone and the water looks like glass again. Water changes tend to reduce this material. But what I am seeing is not a worrisome thing. It is just light being reflected off this material and diatoms rising to the surface. It is my eye seeing the 'invisible as visible' that creates the impression of less than glass water color.
If you were to take a glass of this water and hold it to the light against a pure white piece of plexiglass, you will not see murky water. If you look at it under a microscope, you will have a low count of living water. I think that is a good thing.
At the end of the day, large numbers of cells in the water column ( assuming that it is not particulate matter which is another conversation) means they are getting nutrient. And if they are getting nutrient then they are winning the battle of competitive exclusion. So either a pond is young and going thru it's import and export of community members on the microbe level. Or the pond is not right in design in some detail such as turn over, filter size/design. Or the source water or food is a contribution factor. I think this is not unlike the impossible description of a woman only being a 'little pregnant'! You either are in equilibrium or you are not. JR

[schildkoi]

Quote: Originally Posted by koibooi My 30 ton pond is in fact a three system pond. The two bottom drains feed a 2 ton settlement chamber. From the settlement chamber there are two seperate 110mm feeds, each feeding its own Nexus 3000 and each Nexus has 150 liters of Kaldness. Each Nexus is fitted with an Easy and each Easy hold another 50 liters or Kaldness. That makes 400 liters of Kaldnes. The one Nexus runs a 15 000 l/h pump and the other Nexus runs a 12 000 l/h pump. From the skimmer box a 18 000 l/h pump feeds the trickle filter/shower. Top layer of shower is full of oyster shells and the next two trays are filled with 200 liters each of bio balls. I have three 55watt UV's, one on each return. The pond is three years old and in full sunlight the whole day. I have never had problems with string algae and this is the first time I really had problems with green water algae. The only thing that has changed is that the UV's died. Once I replaced the balast on all three units, I had clear water again.

Based on this description (which sounds like the way I would do it) I am a tad perplexed on the green water. Plenty of media surface area (that remains clean and efficient) and excellent turnover if those are the actual flow rates. The hesitation on those turnover rates is that a Nexus 3000 would have a VERY hard time managing the 15,000 lph (3962 gph). It can be done but the tolerances in water level is very fine. But, even if anywhere close to the numbers quoted shoudl work extremely well so I ams till wondering why the green water is forming without the use of a UV?

As I have stated, the unicellualr algae is dependent primarily on 3 factors, nutrients, Water temperature, and light (duration and intensity).

As quoted, the water temps range from 18 - 29C (64-84F). with water temps also being an indicator (kinda) of light, this range is not really all that high (I used to get water temps in Texas in full sun up to 90F, until I added shade and controlled it to 87F).

Soooooooo, why the green water? Let's get back to the "nutrient" side of the equation for a bit. The system has all indications of being more than ample to handle the nitrification process (ammonia to nitrite to nitrate). There are 3 basic nutrients, ammonia, nitrogen, and phophates. Our typical filter systems handle 2 of the 3. Is there a chance that phosphates are being introduced through the source water? Or even nitrite? I assume that the filter cleaning regime is very regular and thus the settlement is not that issue but in turn could exacerbate the issue if their are "nutrients" in the source water.

Just some food for thoough.

Steve

[koibooi]

Hey JasPR - why are you talking about Florida specifically? I live in sunny South Africa on the southern tip of the African continent and about 18 hours flight from Florida.

Filter cleaning regime is great but you might have hit the nail when you mention Phosphates. I have a Hanna Photometer for Aquaculture (see link below) that I use for all my water analysis. When I use the Phosphate Low Range measure, I am always above the maximum reading allowed 2.50 mg/l. I am however not sure what an acceptable Phosphate reading is.

HANNA instruments® :: Bench