Finally my system is starting to cycle!

I never thought I'd be happy to see bacteria but I'm finally getting my 350 gallon (soon to be possibly be 500 gallons with the addition of a biofilter tank) to cycle. Today is the first day I'm reading nitrites, which of course means there are some nitrosomonas bacteria eating away at the ammonia produced by the liquified starter fish feed I've been adding, and another personal ammonia product I've been adding. Tests showed .25 mg/l nitrites today vs. nothing two days ago. There is some color in my nitrate test but not enough to ready 1.0 mg/l yet.

One thing I've had going against me is originally I was adding ammonia with a surfactant which is a no no, so I decided to drain and start all over. I also have low water temps (65 F.), which isn't as conducive to bacteria growth as higher temps would be. I'd like to get a heater for this large system but don't have the funds at the moment.

Anybody else start a fishless tank and get excited when it there were signs bacteria was getting started? Or do I need to get a life?

I've got fish in a floating cage under 4 inches of ice that I will need to break out once I'm ready. That will be a little bit of fun. And of course I will have to acclimate them to higher temps.

Edited by az9, 06 January 2010 - 02:41 PM.

Bring on the frozen fish.

Bring on the frozen fish.

Don't I know you from another website?

I'm thinking when the time comes to bring them in I will bring them in via several trips with a five gallon bucket after dipping them out of the cage. Then place them into a mostly full 55 gallon drum with the 35 degree pond water. I'll suspend my agitator from the ceiling over the drum. The room the drum will be in stays at 65. F. (Same room as fish tank). My thoughts are it will take enough time for the 35 F. water to warm up to the fish tank temp of 65 F. there shouldn't be any temp shock when I transfer them. I'm also thinking of doing a quick dip into another drum filled with fish tank water and salt before putting them into the fish tank, which could prevent the transfer of parasites.

BTW we are talking at least a few thousand 3/4 inch fish.

Does this sound like a plan?

I remember setting a 55 gallon drum of water outside in cold temps and being surprised at how long it took for it to cool off to air temp, even though i was awarehow much energy it takes to change water temps.

Edited by az9, 06 January 2010 - 07:46 PM.

Yea, I sometimes hang out at "pond moss".
How long will you keep the BG in the 55gal. tank, and what type of food will you feed them.

Yea, I sometimes hang out at "pond moss".
How long will you keep the BG in the 55gal. tank, and what type of food will you feed them.

I will move them into the fish tank as soon as the drum temps reaches the fish tank temp or close to it. The plan isn't to feed them in the drum o r keep them in there very long, it's just to acclimate them to the water temp of the fish tank. Of course I won't do this until the nitrogen cycle is up and running and stable.

In the fish tank I will probably feed them starter feed or a little larger. I've got several sizes left from this summer. I even can feed them ground up freeze dried krill if they seem stubborn.

Edited by az9, 06 January 2010 - 08:27 PM.

AZ, have you ever tried feeding your fish salmon, my PS's love it and with it being high in protein and omega 3 it should be good for them. They are healthy and haven't lost any.

AZ, have you ever tried feeding your fish salmon, my PS's love it and with it being high in protein and omega 3 it should be good for them. They are healthy and haven't lost any.

I'd be worried about transmitting disease. That's how some diseases got spread in the past by feeding trout and salmon fish waste byproducts. VHS was one of the viruses spread this way in Europe or the UK I believe. With the artificial feed the feed is heated up enough to kill any viruses.

Another downside could be higher ammonia. But with your low density of fish you're probably fine.

Az, I use Keta Salmon fillets from Sea Queen which are harvested from the waters near Japan, do you think that there might be a problem with VHS from fish taken from those waters?

Yea, I don't have any problems with ammonia or nitrites, the bead filter is overkill on 100 gal. tank with only 10 large PS's and 2 GSH.

Az, I use Keta Salmon fillets from Sea Queen which are harvested from the waters near Japan, do you think that there might be a problem with VHS from fish taken from those waters?

Yea, I don't have any problems with ammonia or nitrites, the bead filter is overkill on 100 gal. tank with only 10 large PS's and 2 GSH.

Don't know. I do know that part of the world has special problems of it's own.

Hey az9, I'm curious to hear your plans/reasons for adding a separate biofilter tank. My biggest design concern with the Small Scale Aquaculture system is putting the biowheel directly in the fish tank with no way to prefilter. From my understanding of biological filtration, you want to keep the biofilter as clean as possible so that heterotrophic bacteria feeding on mulm won't out-compete the nitrifying backteria. By putting the biowheel directly in the main tank, it must get a fair amount of gunk built up on it.

Anyway, what's your plan?

Hey az9, I'm curious to hear your plans/reasons for adding a separate biofilter tank. My biggest design concern with the Small Scale Aquaculture system is putting the biowheel directly in the fish tank with no way to prefilter. From my understanding of biological filtration, you want to keep the biofilter as clean as possible so that heterotrophic bacteria feeding on mulm won't out-compete the nitrifying backteria. By putting the biowheel directly in the main tank, it must get a fair amount of gunk built up on it.

Anyway, what's your plan?

The water is pre-filtered in a sense, in that it leaves the fish tank via a 'u-tube' siphon into the bottom of the clarifier barrel, before it gets pulled up through the packed netting in a the clarifier barrel via a pump, and gets pumped back to the fish tank where it drops onto the paddles of the RBC to turn it.

However, you bring up a good point, which is another reason to put the RBC in a separate tank, to receive water from the clarifier.

I have three other reasons I want to move the RBC to a separate tank:

1.) To make access to the fish in the tank easier and make cleaning of bottom debris easier if it needs removed. The RBC size was designed for a tank at least twice the width of this one. I could have feed or dead fish lying under the RBC on the bottom and not know it. This could lead to increased ammonia.

2.) To allow me to make the return flow to the fish tank from the RBC tank more of a circular flow for easier cleaning and effectiveness of the 'u-tube siphon." Right now with the oversize RBC and the agitator, the flow in the tank is all over the place which can be stressful to the fish. There could be dead spots too. If I do it right, I may be able to eliminate the agitator (at least at first at low fish loads) by configuring the return flow to not only create a circular flow in the tank, but to aerate the tank. At least that is my plan.

3.) Putting the RBC in a separate tank allows me to be able to isolate it from the tank if I need to do any fish treatments that would be detrimental to the bacteria on the RBC.

Edited by az9, 12 January 2010 - 04:18 PM.

2.) To allow me to make the return flow to the fish tank from the RBC tank more of a circular flow for easier cleaning and effectiveness of the 'u-tube siphon." Right now with the oversize RBC and the agitator, the flow in the tank is all over the place which can be stressful to the fish. There could be dead spots too. If I do it right, I may be able to eliminate the agitator (at least at first at low fish loads) by configuring the return flow to not only create a circular flow in the tank, but to aerate the tank. At least that is my plan.

3.) Putting the RBC in a separate tank allows me to be able to isolate it from the tank if I need to do any fish treatments that would be detrimental to the bacteria on the RBC.

Good points. Being able to create a circular flow is something I've considered a lot in the past. I saw 500-1000g round fiberglass tanks for trout fry at a hatchery in Maine that did this, and it did a great job of moving mulm to a single point at the center where it was removed via a drain. I'd imagine you're thinking the same thing I am -- put the siphon intake at the center of the tank just off the bottom to pick up the mulm where it concentrates there.

One thing to think about if you do create a separate biofilter tank is to be sure that the added volume doesn't put you at risk of an overflow if something screws up. When considering various systems dependent on a u-shaped siphon like you have, I've always figured I'd actually use two siphons side-by-side, with either one capable of carrying the entire flow. That would just give a bit of redundancy in case one siphon failed. Thinking things through to ensure that no failure of a pump or siphon could cause an overflow is actually a pretty fun mental exercise for me.

Good points. Being able to create a circular flow is something I've considered a lot in the past. I saw 500-1000g round fiberglass tanks for trout fry at a hatchery in Maine that did this, and it did a great job of moving mulm to a single point at the center where it was removed via a drain. I'd imagine you're thinking the same thing I am -- put the siphon intake at the center of the tank just off the bottom to pick up the mulm where it concentrates there.

Well no I hadn't thought of putting the siphon in the center but now that you mention it that makes a lot of sense! Thanks!

Here's what I want to do with the gravity flow back to the fish tank, which you are discussing. If there is enough gravity pressure and flow, I'm thinking the holes will work fine to create circular flow as long as they don't get clogged up. If they do get clogged up I'd have an emergency overflow pipe higher than the pipe with the holes, which is much bigger in diameter, but no holes.



From Fundamentals of Aquaculture Engineering - Lawson

I could have set up a venturi drain (one pipe inside another see illustration below) with holes drilled in the bottom and a screen to keep the fish in to periodically drain out the mulm in the center just by lifting one of the pipes, but I chose not to do it this time, but probably will in the future (but not the siphon tube in the center then). The tank is already plumbed for that, but I put a plug on both sides for now. Even more effective would be a tank with a sloping bottom.


(From Principals of Aquaculture -- Stickney)

One thing to think about if you do create a separate biofilter tank is to be sure that the added volume doesn't put you at risk of an overflow if something screws up. When considering various systems dependent on a u-shaped siphon like you have, I've always figured I'd actually use two siphons side-by-side, with either one capable of carrying the entire flow. That would just give a bit of redundancy in case one siphon failed. Thinking things through to ensure that no failure of a pump or siphon could cause an overflow is actually a pretty fun mental exercise for me.

Me too! The whole thing about figuring things out and coming up with alternatives and possibly even improving on someone elses idea is a blast! Unless I'm missing something though I don't think I have to worry about oveflow flooding the floor as the return flow to the fish tank from the RBC will be gravity overflow. The only thing that can fail is the pump (only pump in the system) that sends water from the clarifier tank to the RBC tank. If it fails the only thing that will happen is it will run itself dry to the level it's at in the clarifier tank, which is near the top. No water going to the RBC tank, simply means the RBC will not rotate and overflow to the fish tank will stop. The 'u-tube siphon will also stop flowing, but stay full as one of it's functions via gravity is to keep the level of the water in the fish tank and clarifier drum the same.

As far as siphons side by side the original plans in the book Small Scale Aquaculture- VanGorder for the large 12 foot swimming pool call for two clarifier drums and u-tubes. Perhaps part of that is for redundancy?

Edited by az9, 12 January 2010 - 07:45 PM.

Well no I hadn't thought of putting the siphon in the center but now that you mention it that makes a lot of sense! Thanks!

I could have set up a venturi drain (one pipe inside another see illustration below) with holes drilled in the bottom and a screen to keep the fish in to periodically drain out the mulm in the center just by lifting one of the pipes, but I chose not to do it this time, but probably will in the future (but not the siphon tube in the center then). The tank is already plumbed for that, but I put a plug on both sides for now. Even more effective would be a tank with a sloping bottom.

The trout hatchery tanks I saw did have bottoms that sloped slightly to center, and also had standpipes in the center as shown in the drawing (but I think only a single standpipe, not the double-walled venturi). They would briefly pull the standpipe a few times a day to clear out the mulm.

I didn't realize you had the tank raised off the ground and drilled to allow a direct drain from the bottom. As long as you've got that, it seems like using that rather than the siphon would make sense (as long as you're confident in your plumbing connections!). I assume the original design relies on a siphon because putting a drain fitting in a flexible vinyl liner and raising it off the ground enough to allow room for plumbing would be very difficult.

Here's what I want to do with the gravity flow back to the fish tank, which you are discussing. If there is enough gravity pressure and flow, I'm thinking the holes will work fine to create circular flow as long as they don't get clogged up. If they do get clogged up I'd have an emergency overflow pipe higher than the pipe with the holes, which is much bigger in diameter, but no holes.

Obviously, you can control the pressure at which water returns to the main tank from the biodisc just by increasing the height difference between the biodisc tank and the main tank. Or, if flow/pressure isn't enough, you could use a larger pump between the clarifier and the biodisc, and then use a 'T' and valve to send only part of the flow to the biodisc while sending the rest directly back to the main tank. Or... just add another small powerhead directly in the tank.

Unless I'm missing something though I don't think I have to worry about oveflow flooding the floor as the return flow to the fish tank from the RBC will be gravity overflow. The only thing that can fail is the pump (only pump in the system) that sends water from the clarifier tank to the RBC tank. If it fails the only thing that will happen is it will run itself dry to the level it's at in the clarifier tank, which is near the top. No water going to the RBC tank, simply means the RBC will not rotate and overflow to the fish tank will stop. The 'u-tube siphon will also stop flowing, but stay full as one of it's functions via gravity is to keep the level of the water in the fish tank and clarifier drum the same.

Sounds right. When I've thought through this stuff I was considering single sump systems to provide filtration to a number of tanks. That sort of scenario with tanks at multiple levels and a sump lower than all of them lends itself more to a runaway drainage problem. Given that you've only got 3 components and they're at roughly the same level, I'd guess you can build a pretty foolproof system without much problem. Your concern would be more for a failure to compromise filtration and aeration than to cause an overflow. I'd guess you could figure out a pretty simple system to set off an alarm if water stops flowing from the biodisc container back into the main tank (if water makes it that far, obviously everything upstream is working, too).

As far as siphons side by side the original plans in the book Small Scale Aquaculture- VanGorder for the large 12 foot swimming pool call for two clarifier drums and u-tubes. Perhaps part of that is for redundancy?

I'd forgotten about that detail until I looked at it again just now. I'd assume that they found that they needed more capacity than a single 55g drum would provide, and it made more sense in terms of using easy-to-find parts and keeping the drums easy to handle to use two 55g drums rather than one larger one. I think a redundant siphon maybe makes sense, but I can't see any reason for a whole second drum clarifier just for redundancy's sake.

Guy's, here's some interesting info on biological filters for RAS's, which includes bead filters like the one I'm using, and RBC's like the one AZ has.
http://nsgd.gso.uri....98001_part6.pdf

The only problem I have with my RAS is the low alkalinity of my well water combined with the nitrification process causes the PH to drop, so I have to add 1/2 teaspoon of baking soda per day to keep the PH above 6.

Edited by adirondackpond, 13 January 2010 - 10:39 AM.