SETTLING TANK, INLINE?

[Mmathis]

TurtleMommy again....! Readin' on the road trip back from Thanksgiving in MS -- good time to "digest" pond info (no, I'm not driving ).

Was just reading some on the DOC BIO STICKY, and was wondering how complicated (or feasible) it would be to add something like a settling tank inline before the bio filter.... Seems like it would keep more gunk out of the bio, but would it really, any more than what the main filter does?

Would it change the size pump you'd need? How would you configure the tubings? Do I even know what I'm talking about?

Please, only use "newbie-speak,"

 

[Waterbug]

Depends on the settling tank. Also depends whatever the "main filter" is doing. But in general I'd say settling tanks are almost completely ineffective.

 

[fishin4cars]

Settling tanks are not only very effective but really easy to make out of a 55 gallon drum as well. Pretty simple design. place the inlet about 1/3 of the way up from the bottom. On the inside connect a 45 degree fitting facing toward the center to cause a swirling motion in the drum. I would recommend at least a 2" inlet or larger. Place a shower drain with a valve at the bottom for dumping muck. At the top of the drum place a outlet of double the size of the inlet. 4" would be good for 2" inlet. Have the pipe in the settling chamber set for as close to the center as possible with a piece of turned up pipe set for the water level you want the drum to drain into the Bio-chamber. this will work by itself, but for twice as much separation place scrubbing brushes hanging downward from the top and this will help remove even more muck before going to the Bio- chamber. back flush the settling chamber once a week and you shouldn't need to back flush the bio-chamber but maybe once or twice per season. I'm going to set another one up an a QT tank for the new house, I can build the whole filter, settling chamber with pumps and skimmer for under $400 and feel comfortable I can house 10-20 3"-8" koi in a 2500 gallon pond for a month or two while they are being quarantined or treated.

 

[Catfishnut]

Good Morning Everyone,

WaterBug, Please pardon me on this, but I will have to disagree with your opinion on settling tanks here and agree with Larkin on this notion. After all, what Larkin is stating here is precisely what I have also been touting from my own experience. My own personal design might be a slight variation, but the overall concept is the same. I really do swear that it works very well, if constructed properly.

The main point that I would like to stress is that it is so inexpensive and so simple to fabricate that you can barely, if ever, go wrong. Obviously, you don't just toss it all together in any old way, the person putting it together has to understand a few principles of the design and the physics that make it work.

My vision is based upon the design of a septic tank system, which I have stated a few times recently. Please bare with me while I state the reasons for this, beyond my own personal experience, why this sort of design for pond use should be effective.

A septic system for a home has several partitions or unique stages. First, you have a settling tank which is divided into two or more partitions. The sewage wastes (solids) either fall to the bottom of the first tank or float to its top as scum. Within that tank, these items are broken down by bacteria eventually, but before that process takes place, the main effluent water, clean or cleaner water overflows into the next chamber and the more chambers you have, the more clarified the water is by the time it finds the final effluent discharge or outlet.

At that final stage where the water goes out of the septic tank, the water is almost totally clear of any solid debris or material. It has to be and it must since this water is then directed into the leach field.

The leach field is a series of horizontal PVC or ABS plastic pipes with holes drilled into them. These holes are not large, so any sediment, toilet paper and the nasty stuff could clog them easily if not prevented from getting there in the first place. You cannot have this sort of debrius entering your leach field lateral lines. The only thing going out to these lateral lines in a properly designed septic system is water.

The lateral lines are buried underground and are encapsulated in gravel. These septic systems last for years and years and years before they need to be repaired. So as long as you "siphon out the sludge" from the settling chambers before they overfill, your laterals will last nearly forever. As long as roots don't grow into them or someone with a majorly heavy truck drives over the top and physically breaks the lateral lines below and you don't let your septic tank overfill and send the undissolved and non-broken-down solids into them.

If you can trust this sort of system for such a long time underground with your household sewage discharge, with very little maintenance, why should you not trust the same design system for your pond? How could it be deemed "ineffective"?

I am sure that you guys have at some point in time become familiar with a home septic system. Or at least known someone else who had a septic system. They are not infallible, but when properly designed and maintained, they last for many, many years without major maintenance.

If it works for human waste this well, why shouldn't a derivative of the same design work excellently for just a pond with mostly clean water and very little debris? I already know that this does work as this is one of the things that I have implemented long ago with my bait tank system and found it to function to my advantage. I would hate to see others pass this option by when it can be such a blessing at such a minimal cost and design involvement.

My apologies for being so bullheaded about this one, lone specific topic. I do want to ensure that everyone examines it very closely because I sincerely believe that it holds a great deal of merit.

More than that, I really and truly want to help everyone with their projects as much as I want others to help me. So, I want to discuss all of this so that I can learn, too.

Gordy

 

[koiguy1969]

altho settling tanks can be a useful addition to a filtration system.....myself, i would use a well made prefilter before a settling tank...even if you clean have to clean it every day or two...once its cleaned the biomatter collected is eliminated from the system.... fecal matter, and other biomatter doesnt know where its at, wether its in the pond,.a settling tank,.or a biofilter. as long as its in the system its beaking down and releasing ammoniums. the more often these are eliminated from the system the easier time the biofilter has keeping up with its task.

 

[Waterbug]

Gordy, I always appreciate serious discussion which you always provide. My opinions should never be taken as fact, I don't think of them fact, just what I believe today.

Because there are no absolutes I said:

Depends on the settling tank. ...But in general...

So I agree 100% with you when you say:

...it works very well, if constructed properly.

That's kind of my point.

Larkin's example doesn't mention how many GPH can be pushed through the tank or how debris is moved from the pond to the tank. I assume a bottom drain. Well a bottom drain only pulls debris from maybe a 1' radius. Other water flow is needed to direct debris to the drain before it can get to the tank. IMO it's not as simple as just hooking up a 55 gal drum.

Define effective.
The other issue would be to define what "effective" means. If the goal is to remove 5% or less of stuff from the pond then sure, I'd say a settling tank is effective. If the goal is to remove 50% I'd say settling tank are not effective. Even vortex filters aren't that effective.

Settling tanks are for fish poop, not suspended particles.
The best a drum is going to do is trap big heavy chunks of fish poop. There no way it can trap suspended particles because the turbidity in the drum is probably 1000 times more than in the pond. A pond owner may see really fine stuff in a settling tank but that's only because trapped fish poop has decomposed. Only takes a few days in such a turbid environment.

There was a time when cleaning ponds that I kept waste water from the Silt Vac in a large tank (300 gal I think) to let the water settle so cleaner water could be pumped back into the pond. It took like 8 hours in a perfectly still tank for the water to start to clear and 24 hours before I'd thought the water clear enough to pump back in. So to me, a 55 gal drum, with a constant flow isn't going to remove suspended particles.

Settling tanks always had a single function...remove fish poop. They have to be flushed daily and flushing flow on the pond bottom is needed. I think most water gardeners think they will make the water clearer and for that I think they are ineffective.

Why is a tank different from a pond?
In order for debris to get into the 55 gal drum the debris first has to settle to the pond bottom and be pushed to the bottom drain. It seems more effective to me to have the flush valve right there, on the pond. I don't see any improvement in having another chamber and trying to get the same stuff settle a second time. Why?

There are different kinds of vortex filters of various complexity that try to push suspended particles out but even they are not very effective for suspended particles.

Better choices.
Back to fish poop...once you get the poop into the bottom drain I think a sieve filter is way more effective than a settling tank. Instead of the poop sitting in the tank for a day waiting to be flushed the poop is removed instantly 24/7. Poop start decomposing right away so even if flushed daily there is still a lot of decomposition which is what we're trying to stop. With a sieve filter set up right you could go weeks, maybe months before any cleaning is needed. To me that's much more effective which in comparison with any settling tank.

Well, that's just my thinking. I don't mean to rain on anyone's parade. If you believe in settling tanks then you should go for it. Isn't going to harm anything.

 

[Mmathis]

Explain "sieve" filter, please

 

[Waterbug]

I provided a link that explains it better than I can. Google is also useful.

 

[fishin4cars]

Very useful and far more agreeable post IMO there waterbug! Settling tanks can be effective, but as Waterbug stated there are many variables. The one I made and played with was on a fairly small pond with a low GPH flow rate. It was used as an experiment just to see how much MORE gunk I could remove before the Bio filtering and it did remove a good bit. I believe in MY case it romoved about 30-40% more poop and gunk than I had before I used one with no settling chamber, and It did need flushing fairly often but was only a small bit of water to replce when I dumped the build up at the gottom of the tank. I agree though that if the purchase can be made a sieve filter would be FAR more effective and take up far less room to be equally effective as a Vortex or settling chamber. Google and research is a necessity when researching advanced ponds of this nature. I'm in that boat now, I really want to build two identical ponds in the 7500 gallon to 10,000 gallon size range. I'm exploring several different types of filtering possibilities. I think these kind of discussions are helpful as there is some debate and new ideas born. No one pond builder has the perfect most effective way to filter, they design what the can budget and what best fits there needs.
One thing that needs to be addressed in this paticular case is the pond is 50% turtle habitat along with fish. So some turtle poop needs to be kept in mind as well as fish poop. In this case I think some type of GOOD pre-filtering is a must, but IMO I think that Bog filtering instead of a true Bio chamber would be nice as it gives shallow areas for the turtles to safely explore and would be very effective in helping to clear solids, and fines along with the heavier waste load with the turtles. Also using a settling chamber or vortex would remove a good bit of the heavy solids and leave the breakdown for the plants to use up in a bog situation.

 

[Waterbug]

A sieve filter is pretty easy to DIY and cheap. I'd guess it's cheaper than a settling tank and I'd say easier, but close to the same effort.

 

[Mmathis]

Hmmm, was reading about BOG FILTRATION, and it DOES sound interesting. But was wondering, if the sediment is allowed to accumulate & decompose naturally, how do you factor in the EXTRA load from turtle waste (and it's a lot!)? One end will service 2 turts, while the other end will service 6. Also, what happens if there are internal parasites passed in their poop? I have NO idea what normally happens to "worms" in water, but can't chance that they would survive to continue their life cycle since boxies use their water as toilet.

 

[Waterbug]

Bog filters are excellent for water gardens, but yes, their draw back is accumulation. To reduce the issue a good pre filter is used and also making it so large that times between cleaning is reduced. They can go many years without needing to be cleaned.

People with high fish loads don't use bog filters because the waste is still in the pond and that isn't acceptable for them.

 

[Catfishnut]

A sieve filter is pretty easy to DIY and cheap. I'd guess it's cheaper than a settling tank and I'd say easier, but close to the same effort.

Waterbug,

I have viewed that same video of the sieve filter a few weeks back. I really think the concept is great, but since I first saw it, I haven't been able to come up with a convenient way to apply it to my bait tank pond. I am still contemplating this, however.

Gordy

 

[Catfishnut]

Gordy, I always appreciate serious discussion which you always provide. My opinions should never be taken as fact, I don't think of them fact, just what I believe today.

Waterbug, thank you. I do feel the same and note that my ideas and opinions are just that as well. I very much enjoy the discussions on the subjects. I think that they open up many new avenues as well as present new ideas and possibilities to everyone, including myself.

Larkin's example doesn't mention how many GPH can be pushed through the tank or how debris is moved from the pond to the tank. I assume a bottom drain. Well a bottom drain only pulls debris from maybe a 1' radius. Other water flow is needed to direct debris to the drain before it can get to the tank. IMO it's not as simple as just hooking up a 55 gal drum.

This is one of my personal dilemnas with my bait tank pond. Since the tank is a hard-walled structure with a perfectly flat bottom, I am going to have a difficult time directing the debris to the drain (it won't exactly funnel down to a lowest point in the tank like you could manage with a pond liner). I also do not wish to install a true bottom drain on this tank. Because it is not going to be entirely permanent (I want it to be relocatable to an extent) it would not be a good idea to have a drain fixture hanging out the bottom of such a heavy and large tank. It would just get smacked up or broken off during transport. Eventually it will be permanent out at my cabin, but not until I have finished the entire design and construction.

Settling tanks are for fish poop, not suspended particles.
The best a drum is going to do is trap big heavy chunks of fish poop. There no way it can trap suspended particles because the turbidity in the drum is probably 1000 times more than in the pond. A pond owner may see really fine stuff in a settling tank but that's only because trapped fish poop has decomposed. Only takes a few days in such a turbid environment.

This is a very good point. My hope is to design a baffle structure that will drop a very high percentage of even the smaller suspended particles so that they will sediment out and fall to the bottom of the tank while not hindering the total flow of water (so that water flow is never restricted). This will take some doing in a round barrel, it won't be so simple to fabricate the baffles. It would be much simpler if the barrel was square or rectangular. My original design was to utilize layers of coarse rock as the baffles and blockades. I will have to see how that works out.

There was a time when cleaning ponds that I kept waste water from the Silt Vac in a large tank (300 gal I think) to let the water settle so cleaner water could be pumped back into the pond. It took like 8 hours in a perfectly still tank for the water to start to clear and 24 hours before I'd thought the water clear enough to pump back in. So to me, a 55 gal drum, with a constant flow isn't going to remove suspended particles.

Yes, that is certainly quite an obvious point. You would almost have to have an enormous settling tank with an extreme number of baffles compared to the size of the pond and the GPH that the pump is moving in order to force the fines to sediment out. I don't know what percentage of fines my sytem will be capable of. Obviously not 100%, nor 90%... But, maybe I can get it to 75-80% if I work very hard on the design.

Why is a tank different from a pond?
In order for debris to get into the 55 gal drum the debris first has to settle to the pond bottom and be pushed to the bottom drain. It seems more effective to me to have the flush valve right there, on the pond. I don't see any improvement in having another chamber and trying to get the same stuff settle a second time. Why?

For me, it is a matter of necessity because of the limitations this hard-walled tank with a FLAT bottom presents. But, for a ponder, that would make a great deal of sense. A ponder can engineer the terrain and the slope of the bottom of the pond to serve them better in this regard. I don't have that luxury, exactly.

Better choices.
Back to fish poop...once you get the poop into the bottom drain I think a sieve filter is way more effective than a settling tank. Instead of the poop sitting in the tank for a day waiting to be flushed the poop is removed instantly 24/7. Poop start decomposing right away so even if flushed daily there is still a lot of decomposition which is what we're trying to stop. With a sieve filter set up right you could go weeks, maybe months before any cleaning is needed. To me that's much more effective which in comparison with any settling tank.

I replied to the notion of the sieve filter already in another post. But, I will add that I think it has some serious potential for me or others. To an extent. What happens when algae starts to grow on such a fine mesh filter or screen? Even something as coarse as a window screen would require continual maintenance, would it not??? I like the concept, but I have some doubts about the merits of the system as it is shown in the video.

For certain, you have me thinking yet again, Waterbug! And, believe me, it is good!

Gordy

 

[Waterbug]

Flat or slopped bottom doesn't have very much to do with collecting most debris. Most people do seem to think gravity is an important force in ponds but buoyancy is the real force. Water movement pushes debris to drains, not gravity. Even in a vortex filter, with a bottom more than 45 degrees debris will still settle on the sloped floor and stay there without water movement.

There's the same problem with suspended particles, most people seem to think they'll settle if this or that is done. Suspended particles are exactly like dust in air. Particles in water are heavier than dust but buoyancy cancels that weight. They are basically weightless. In perfectly still water, enclosed in darkness to reduce thermal currents, it can still take a long time for these particles to fall to the bottom.

Sieve filter screens do have to be kept in the dark to prevent algae growth. People using them talk about bio film growth being an issue. Seems to be related to the mesh size, smaller closes faster. So they do need to be cleaned every 20 to 40 day range it seems. So people have designed the screen on a rotating belt so when the screen clogs water is diverted causing the belt to rotate. Pretty complex. The simpler method is to place a lawn sprinkler head under the screen and have it go off for a minute or two every couple of days. That seems to reduce for cleaning.