6 replies to this topic

[silly]

Setting up a 3 tier breeding rack currently with 6 x 100L tanks with a 200L sump. The tanks are drilled with 20mm bulkheads in the top rear. What diameter do I need to make the outlet pipes? Keep it at 20mm or increased it to soemthing larger?
What size return pump would I need? And piping size?

I was thinking of connect each row (2 tanks) to an individual 25mm horizontal drain into the sump. Is that an adequate size for the drain?

[humbug]

The rules of thumb I use for initial sump and plumbing sizing

 

1.  Sump volume should be a minimum of 25 - 30% of total tank volume.  Your 200 litres sounds good.

2.  Aim for a rated nominal pump capacity of 6-8 times total tank volume per hour.  If you have a large head pressure (ie very tall rack) you may need to check pump flow charts.  Depending on fish you are keeping, you probably want to aim for an actual water turn over of at least 3 to 4 times per hour, based on the supplied flow charts.  So for your setup I'd be looking at pumps with rated nominal flow of 3500 - 5000 litres per hour.  Need to check out those flow charts though.  In looking at pumps, consider running costs as well as purchase price.  These things run 24 hrs a day, 7 days a week, and an inefficient pump can add a hell of a lot to your running costs.

3.  Plumbing size from pump to tank - use your selected pump to determine this.  Take a look at the outlet size from the pump and base your pipe size on that.  Any smaller and you are unnecessarily constricting the flow and reducing the pump output.  Any larger and you aren't achieving anything except adding to the volume of water that will backflow to your sump when the power is cut. (I personally don't like to use a check valve on these lines - I think it adds too much to backpressure and reduces the efficiency of the set-up).

4.  Plumbing size from tank back to sump - at least one size larger than the plumbing to your tank.  If you combine multiple outlets into one drain - increase the drain sizing further.  You want the least possible restriction of flow back to sump.
 

[humbug]

So for your set up, I'm guessing you will end up with a 20mm run from your pump to the tanks.  20mm bulkheads will be fine, but I'd personally be running 25mm lines from them, and then upsizing to 32mm or 40mm if you combine them to a common hard-plumbed drain back to sump.  That allows for build up of crud in the pipes over time without restriction to flow.

The alternative that a lot of people use is just to use individual flexible hose from the bulkheads straight back to the sump, although hard plumbing gives a neater finish.

[malawiman85]

I had a 3 tier rack like yours with 6 x 150L tanks the sump was 200L and came with a 2000L/H pump... It was totally inadequate. I had another couple of pumps laying around a 3600L/H and a 4800L/H. I thought the 4800 was too much. The 3600 was pretty good though.
Cant remember what the 3600 cost to run. I think the 4800 consumed 90w an hour which is a lot of juice for 6 tanks running 24/7. More economical to use 6 × 10 - 12w power heads in closed systems. Gives better control of flow, oxygen and disease spread. The issue withthis method is you have to heat individual tanks rather than heating the sump.
I tend to think a lot of heat loss would come from the movement of water to, through and returning from the sump.
Im not saying multi-systems with sumps arent great but I reckon in setups like these its better to keep tanks seperate.
The only occasion I would use a sump now is on a big display tank over 1,000L, a really big breeding setup or a marine tank. For most other setups I reckon there are better options.

[silly]

Thanks guys, great info there.. I think I have a good start now.
I'll look for a ~4000l/ph pump with a bit of head for the output of the return filter. Hope I can get 16mm outlet for the return pump which should give me enough drainage with the 20mm bulkhead?
Also I Just have the single Bulkheads for the drain so I will have to create an inlet to go above the sides of the tank. I do like the idea of flexible tubing for the drains tho, I'm a bit restricted with access to back of the tank so flexible drains suit me. I take it will be the black anti kink tubing? Where do I get that from at a decent price? Heard it can be pretty pricey..

As for the reasons why I've gone the rack and sump route is i already have quite a few divided and single tanks with individual heaters and sponge filters.. Was trying to reduce the power with the amount of heaters in the room so thought the sump option would be good. I can also ensure maximum filtration effectiveness with the sump in the form of jap mat, k1 and ceramic tubes.. I have a couple of 300w Eheim lying around I was going to utilise in the rack too. I guess heating the room is another option but I am looking at high 28-30 temperatures for L numbers etc.. Not sure a room heater would be more cost effective?
Cheers

[humbug]

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Edited by humbug, 03 August 2016 - 08:03 AM.

[malawiman85]

I think the general consensus is its cheaper to heat the water than the room.
Id rather run 6 x 200w heaters or a couple of 300s rather than have a 2000w room heater on all day.
Probably a matter of horses for courses though.