flow through the sump

[kwirky]

I'm confused as to how fast water should be moving through a sump. There are so many factors involved. How much water should flow through it for the skimmer to have stuff to pull out? If that needs to be high, then how about people who use low flow through their sumps to cut down on noise/micro-bubbles?

Anyone with their experiences with slow/fast flowing sumps and what they liked/disliked?

[cprowler]

I think you want 3 to 5 times the display volume per hour. Check out this link.

http://www.melevsreef.com/what_sump.html

[Joe Reefer]

I have to agree with Bill, all though I have heard figures higher than that.

I tried for 10+ turnover though a 29 gallon sump, I ended up with 5 baffles to finally stop microbubbles.

[SeaHorse_Fanatic]

I have just over 3 times flow through my sump. My reasoning for low sump flow is so that the skimmer has more time to skim the water, compared to high sump flow.

Anthony

[scumchug]

I'm running 12X flow with no noise and no micro bubbles

[Delphinus]

IMO there's no real advantage to having a high flow through the sump. It's not bad if you can do it, but to me I'd rather look at flow within the tank with things like wavemakers, powerheads, waveboxes, Tunzes, closed loops, etc. etc., and just have the sump as a place to run the skimmer, heater and any other filters or equipment (phosphate reactors, carbon, etc.)

Plus, it's just easier to keep the microbubbles and noise in check. For example I have somewhere around 9-10x volume turnover on my 115g cube tank right now and it sounds like a whitewater rafting river in the sump, and if I take out the filter sock, the tank is literally white with microbubbles. A longer sump would work but I'm restricted to what can fit in the stand so I'm stuck with about 28". I can't put more baffles in and still hope to fit my skimmer.

I think I have about 8x volume turnover on my 75g but because I'm using a 48" sump I don't have the microbubble problem on that tank. It's just sheer luck though, had the sump been any shorter there would have been a microbubble problem. It too has a bit of a whitewater river rapids thing going on. Between these two tanks my basement sounds like Takakkaw Falls. I'm never running sumps with over 5x turnover on any tank I set up next. :lol:

[andsoitgoes]

I agree with Tony - With the sump, you want to have the water in there as long as possible for heating, skimming, etc.

I've got about 1.5x turnover if not less - s'all I need the system for it to skim, heat, sterilizer and push through carbon. It's in the bedroom so it's quiet, no problems, makes me a happy camper :)

Every now and then it sounds like a big monster is sucking dry the bottom of a slurpee container, but that's easily fixable, sometimes - usually without TOO much swearing and adjusting of chaeto :P

[digital-audiophile]

I have around 3 times turnover per hour with my sump. This is becuase I had to trottle back my return pump as I only have one 1" drain on my 90 and any more flow back into the tank causes a flood :p The nice slow turnover works well as I have zero microbubles back into the tank.

[danny zubot]

Is the turn over rate determined by the tank size or the sump size? My tank at 65 gallons means I have almost 14x turnover, but my sump at 25 gallons gives me a 36x turnover rate. (Mag 9.5 return)

[Delphinus]

I look at it as tank volume plus sump volume (or.. well .. "volume of water in sump" since a sump isn't run full). So that's more like 10x turnover per hour in your case Danny, although it's probably more like 8-9 times since the sump return is likely putting out less than 900gph at 4'-5' of head pressure.

[danny zubot]

I only have 12" head pressure because the sump is behind the tank on it's own stand. I'm a bit high on the flow side but I don't have too much in the way of micro bubbles.

I'm just wondering if my skimmer would pull more sludge if I somehow slow down the flow?

[digital-audiophile]

The way I roughly calculate mine is that with my Rio 32HP pump rated at 1300GPH at 6' head I have it throttled back to about 1/4 open via ball valves (~325GPH) with 90 gallons in the display tank I figure this entire volume should in theory pass through the pump 3+ times an hour. I have a 55G sump with ~30G of water in it, I did not take this volume into consideration, allthough perhaps I should.

[kwirky]

Ok, so now I'm trying to guestimate what kind of turnover I'm really getting through my sump and how to throttle it back if I can.

It's a 120g (48x24x24) with a mag 7 for the return. The pump's output is 3/4", which first goes to a 1" adapter. Then it's two 1" 45's (sweep 90), then a 1" check valve and a 1" ball valve, finally adapted back to 3/4" for the gasket, then back to 1" for the pipe that rises to the upper regions of the tank, then out a 1" 90.

Basically it's going through two 1" 45's and a 1" 90, a 1" check valve and a 1" ball valve. I'm guessing I'm getting about 500gph through it so about 4x water turnover.

Would turning down the ball valve (on the output of the pump, no ball valve exists on the input) shorten the life of the pump/impeller in any way? I'm thinking that would be my simple solution to eliminating some noise.

I think I have microbubbles because ****loads of 1/4" sized bubbles cling to the nasty fiber-like that grows on the various plastic things in the tank and when I blow off the rocks with the turkey baster bubbles get blown out from the undersides of the rocks. I have no baffles in my sump unfortunately. I'm planning on getting some eventually but I'd rather upgrade to a larger sump at the same time if possible (when $$ happens).

[Delphinus]

RC has a head loss calculator if you really want to check the loss, but I'm thinking 500gph is a reasonable guesstimate anyhow.

Putting a ball valve on the output of a pump is totally fine. It's just additional head pressure. Interestingly most pumps seem to draw less power when throttled back this way, basically it's the speed of the water that seems to be directly related to consumption, not how high the water is being lifted. I'm not sure if this is true for all pumps but most pump curves that I've looked at seem to indicate this.

If the issue is noise though, I'm curious how you have the overflow setup (Durso, Stockman, etc. ?) and how the pipe enters into the sump. If the pipe comes straight down, you get this splashing effect. Sometimes lowering the pipe so that it exits just under the water surface can help. One thing I've found that makes a big difference is if you can have the pipe come in at an angle, then the water "slides" into the sump as opposed to "falls/splashes" into the sump.

[Der_Iron_Chef]

You can limit the output of your pump with no ill effects. It's only when you limit the input that you start creating problems for the pump.

[kwirky]

You can limit the output of your pump with no ill effects. It's only when you limit the input that you start creating problems for the pump.

thanks. gonna turn it down a bit right now.

and about those filter socks for the returns, how often should they be changed?

[danny zubot]

Mags aren't pressure rated so putting them under additional load would shorten their life shouldn't it? I killed a mag 18 in pretty short time using on a becket skimmer. Personally, I'd get baffles or upgrade the sump like you said. Another trick I use to cut down on micro bubbles is placing LR rubble around my return pump. Then I place my carbon bag on top of that.

[Delphinus]

Hmmm, mags *should* be able handle a little bit of pressure. I don't think I would dial it down past half, but it's just perceived as head pressure. They're usually awesome little workhorses. I wonder if you had a bad pump Danny? I've been running my beckett skimmer for like 4 years now on a Mag18. IME Mags usually just go and go and go. I finally threw out a mag 7 after about 10 years of use (I had bought it used in like 1998 or thereabouts) about a year or so ago, but it was because the impeller had developed a wobble, and basically had ground out the bearing hole. Ie. I couldn't just get a new impeller as the hole for the impeller shaft actually became oval.

[danny zubot]

I wonder if you had a bad pump Danny?

It very well could have been a bad pump. I was glad to get rid of it though, they aren't the most energy efficient pumps out there.

[Delphinus]

No, indeed, nor very quiet for that matter. I was trying a mag5 in my FW tank (upstairs near my TV) and the hum coming from the tank/stand was intolerably loud. I ended up having to switch it out for a Sedra pump (still not 100% better but at least it's possible to hear the TV over it!)

[danny zubot]

Thats why my tank got banished to the basement.:lol:

[Pescador]

thanks. gonna turn it down a bit right now.

and about those filter socks for the returns, how often should they be changed?

My turnover is about 4.5x per hour and my return is split into two 7" dia. filter socks (the output of the two skimmers share one as well). My turnover seems to keep the cheato happy and the socks take care of the bubbles.
I throw the 3 filters into the washer once a week and change them out with a fresh set.

[danny zubot]

My turnover seems to keep the cheato happy and the socks take care of the bubbles.


Does lower turn over create a better environment for growing chaeto?

[Der_Iron_Chef]

My turnover is about 4.5x per hour and my return is split into two 7" dia. filter socks (the output of the two skimmers share one as well). My turnover seems to keep the cheato happy and the socks take care of the bubbles.
I throw the 3 filters into the washer once a week and change them out with a fresh set.

Do you use detergent when you wash them? I would think that you shouldn't.

[Delphinus]

Nope, no detergent. I do use bleach though. And I run them through another cycle without the bleach just to make sure they are really good and rinsed.

[Pescador]

Does lower turn over create a better environment for growing chaeto?

I know people recommend having it tumbling in a faster flow but I turn it over by hand once in while and I'm taking out about a grocery bag full a month.