SLO Vs Pump in Fishtank

tcshad

I was just reading another forum where their guide offers an interesting suggestion

They say that rather than using a SLO, you should use a pump in the FT to pick up the solids and "chop" them up into smaller particles to assist in the breakdown and conversion into nutrients.

Has this been discussed at all and does anyone in the know have an opinion? I secretly thought that you'd eventually end up with a little pile of fish poop under your SLO outlet on top of your media.

This suggestion kind of reinforces my opinion.

Stuart Chignell

You want to test the solids waste from your fish tank as gently as possible. The rougher time that solid waste experiences before it its filtered out the harder it if to keep your water clean. To this end make sure that drain velocities are kept to a minimum (but not so slow that solids settle in the drain). Keep the number out bends and fittings to a minimum. If you have a bend try and make it a sweep instead of an elbow. If you have to use elbows use two 45 degree elbows instead of one 90. When the water enters the gb and exits the drain have it do so gently and don't allow it to fall from height. Essentially do everything you can to reduce the turbulence of the drain water and hence the forces that the solid waste is subjected to. On no account have a pump in the ft.

There are many systems that are working quite well that ignore some out all of these guidelines but you will find that they are quite lightly stocked. There are many more that have persistent fish health problems due to the high levels suspended fine solids in the water column.

earthbound

Cost, plus space and simplicity... Are you designing a commercial system or something simple for your backyard? Having a pump in your fish tank can be a very effective way to set up and run your system, despite what some theorists say.... :raspberry:

I think that claiming it is advantageous to cut up the solids in a pump is possibly pushing the "advantages" a bit, but there are others. The simplicity of a system with a pump in the fish tank pumping up to a bed and draining back can't really be beaten. If you use a SLO then your tanking a chift pist style of system and that means that you need more components to your system, a sump tank etc.

tcshad

Stuart, your explanation may as well be the absolute polar opposite of what the other person recommended... Whilst their description makes sense in that smaller waste = higher surface area = faster conversion to nutrients, yours doesn't other than to say it keeps the water clearer... Other than water clarity are there any other advantages?

EB I was planning a chift pist system but to be honest at this stage I haven't completely decided. I'll need to get more opinions now that I've moved from 1 IBC to 3.

my thread viewtopic.php?f=18&t=12452&start=30

earthbound

Stuarts post is about keeping the water at best quality for fish, he's correct in most of what he says... Whoever told you polar opposites is pretty wrong... :dontknow:

Stuart Chignell

:raspberry: :evil:

Yeah I knew I would get that. Seriously though the densities that you recommend are low and the systems of yours that I can think of only have a few gbs and hence only a few fish (if run sensibly).

You can run a pump outside the ft almost as simply as you would run one in the tank. Ft to first bank of gbs siphon to second bank of gbs/sump (ie gbs with an area of no gravel where pump is.

Alternatively if you are running a CFCF (constant flood, constant flow) system them it could be just as simple.

earthbound

I don't know that I get the system your explaining..

Well you did say you expected it...

Have you set that up and compared them them? Haver you run a system like this to find out what other potential problems there may be with it long term? It's easy to compare real systems with theoretical ones and say the imaginary ones are better.

Stuart Chignell

Basically you want the solid waste to go into the gb and stay there. The gb is a filter and it is easier for a filter to filter big things rather than small things. If you chop up your solids into little pieces then there is a very good chance they will pass through your filter. If this happens a little bit then it is not a problem if it happens all the time then essentially your fish are always breathing dust or actually s$#t.

For some fish this is not a problem. For trout it is. I don't know about barra, perch or cod. Given the choice though I'd rather give them clean water than dirty.

Stuart Chignell

The one I had in mind its in your book and on your dvd. It was one big tank with a gb above it about a third the size of the tank.

These aren't theories. The techniques and principles come from the aquaculture industry, waste water industry, chemical processing industry among others. They are also one of the reasons that people from the aquaculture industry are so adamant that gbs won't work in commercial ap. There I think they are wrong because there is research to show how effective gb filters can be.

I can't speak for species that I havn't kept but for trout this is a concern.

tcshad

ok that makes sense... but doesn't answer my question about the finer solid particles being more easily mineralised by the worms and/or bacteria in the growbed. Or my question about the growbed essentially ending up with a large pile of fish poop under the SLO outlet.

Not having a running system I don't know if this is ever an issue for anyone.

nih

From my experience i can tell you the water and bottom of the fish tank in my system using a SLO is cleaner than my systems with pumps in the fish tank.
I agree with what stuart is saying about stiring up the solids as little as possible. The more they get stirred up the more they tend to stay in suspension in the water even after the water passes through the grow bed.
I don't have any piles of fish poo under my SLO outlets but i can see that it may be possible for this to occur.

Lyndon346

tcshad wrote:

ok that makes sense... but doesn't answer my question about the finer solid particles being more easily mineralised by the worms and/or bacteria in the growbed. Or my question about the growbed essentially ending up with a large pile of fish poop under the SLO outlet.

Not having a running system I don't know if this is ever an issue for anyone.

If you have large piles of fish waste under the outlet in the grow bed you probably have to many fish for the system to cope with.

Stuart Chignell

Many systems use to have a distribution grid to prevent the build up of solid waste in one spot in the gb. Many of those people don't bother now.

RupertofOZ

And many systems... end up with a build up of solid waste in one spot in the gb.... or a root ball the "pools" water around it... :wink:

DecalsbyJT

in all my GB's I use a central pipe going down the center, it has holes on the bottom and distributes the solids down the entire length of the GB... not a grid, just a single pipe....

seems to work really well

jT

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