Advice needed, canister or sump

Sump all the way. You don't need ridiculous flow rates with a sump as you do with a canister. The reason a canister has higher flow rates is because of the poor oxygen environment inside them so the water needs multiple passes an hour. a Sump is oxygen rich if set up correctly so less turnover is required. More oxygen = more efficiency. What is being added here with nitrification, NH3>NO2>NO3.

Also you drill pilot holes in submerged inlets with a sump to not flood your house. You also make the pump compartment smaller than what the headroom of the tank is to avoid flooding. Overflow you want 40mm or bigger. If you have small fish you place a piece of pvc pipe full of holes in the overflow. You also don't have to use glass for a sump, one of my tanks has 2x220L barrels for a sump and the added water volume is a godsend, that monster is such a pleasure to work on as you can't break anything.

 

I still believe the sump is the best route.. even if you have to drill the holes slightly bigger
The fish you plan on keeping, you will be grateful for the benefits of the sump

If the plumbing is right and you mark your 'safe' water level on the sump, it will not overflow
We have 3 X 2m sumps and a 1.8m sump.. never overflowed

As for fish blocking the overflow, if you have smaller fish like i have in the pup tank, a little bit of eggcrate on the overflow stops them going in

 

What would the optimum flow rate be for a sump?

 

I like it around 4-5 times an hour.

Here's a calculator.
https://www.yihufish.com/fishkeeping-articles/filter-flow-rate-calculator/

 

Oops... My setup is in the region of 250lts (Sump included) and i'm running a 4500ltph pump... So i guess i need to scale that back by 50%....

 

Well, I think the recommendation is something like 4-6 times the volume of your tank but there's guys out there doing 10 or more. I guess more is better, unless of course you generate so much current in tank that your fish gets a constant workout
Lots of ways around that though.

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More isn't always beter. If your flow is too fast the water needs to pass over the bio more than once. The longer it stays in contact with the bio media the beter. Within reason of course. I set up my sumps for 4-5 times and hour tank circulation but in the sumps itself, it has a recirculator that recirculates 8-10 times an hour inside the sump with a wet dry trickle filter. Any ammonia or nitrite going in isn't coming out as anything else but no3.

 

That makes perfect sense, I didn't even think about that. How does the sump recirculation work, if I may ask? Between what sections are you recirculating

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The blue line is the water route a normal sump would follow, the red is the recirculating trickle filter. I'm running it on 2 pumps right now but going to get a bigger pump later that can do both, they arn't cheap.

 

If you suspect low flow is causing issue with water quality, I would first add an air stone or two before upping flow in a tank.

Later Ferdie

 

Looks relatively easy to do, ill have a look at getting it set up as well. Thanks for the idea!

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Hi Ferdie, quick derail.

I don't have an airstone in my tank, but have spray bars and a lot of surface agitation. Will that be sufficient?

If I put an airstone in the sump, will it be as effective as one in the tank?


Thanks!

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Yeah almost the same ... what is nice about the airstone ... it creates an upward circulation, but your spray bar should do just fine for the needed surface movement.

One of the things that I have found with the canisters ( most of them blow out on the surface ) the deeper tank can have almost zero substrate circulation. Just by dumping an airstone in the furthest corner fixes it.

By the sound of things you have ample O2 exchange on the surface ... so probably no need for one in the sump then.

Later Ferdie

 

Hi All

Quick update, I ended up getting a canister and a sump. I received a tank and a few other items from @Barry Roux (thanks again bud, you really helped me!) and had to convert it to a sump. In the interim I got a canister as well (good price, couldn't refuse) and that allowed me some much needed time to build the sump.

The sump was installed in the week. No bio media yet as I got a little surprise in the form of a few fry I discovered when I drained the tank to prep for the sump, as well as 2 holding females I discovered when everything was up and running again. The fry and females were moved to the sump for now.

So all in all things worked out great! Ill make do for now and continue with the sump when I made a plan with the fry

Thanks to all for their valued input and assistance!!

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I've noticed the low/no substrate circulation in my tank. Want to plump the sump return a bit lower in the tank to sort it

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Very cool - so the sump is now a grow out tank in the same water column .. why not !!!!

 

Yep. It was that or chuck them in the guppy/endler tank. Don't really have a other proper place to put them.

Lucky I did build a small isolation type section in the sump, but it didn't help much with the fry and 2 holding females. They all have their own section of the sump now. The females were actually aggro when in the same section

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Be careful of plumbing the return of the sump lower... remember a sump is not a closed circuit like a canister
I have seen sumps overflow not only from the overflow box but also gravity building up in the return pipe

You lower the spray bar of the canister and leave the return of the sump at the surface

You can also try turning your spray bar of the canister that the holes face the bottom ( i have done that before and it works) and that will give circulation in the substrate
Alternatively you can get a small wave maker and strategically place it in the tank so that it blows the dirt to the side of the intake of your filter

 

Will a small hole above the waterline in the return plumbing not work to break the siphon when the pump goes off?

A wavemaker is also a good idea though! Have a lot of rock in the tank now and will need to get some decent flow in between all the rocks

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Yes it works but usually the return is 3cm or so below the water level
If you take it down lower into the tank gravity can get the better of it or if that little hole gets a bit of dust or dirt in it you have disaster
I swear by sumps... but I like to play it safe with a sump

Besides, if you have a lot of rocks, your wave maker is (to me) a necessity

Personally, I would turn the spray bar of the canister in a way that the holes face down at an angle and cause current lower down in the tank. Play around with it until you find the perfect angle for your setup
Leave the return of the sump at the surface for water agitation and safety of overflowing your sump
Place a wave maker on the opposite side of the intake to the filters and you should be fine