Sump basics

scottward

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Oct 26, 2007
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RukoTheWonderDog helped me out in another thread, which I decided to move to here:

Here are some sump basics-

The level of water in the tank is the key. When the water level in the tank exceeds the top of the overflow, it gets dumped into the sump. The pump returns that water thus increasing the water level in the tank. The faster you pump water into the tank, the faster the water level rises, and the faster it spills over the overflow & drains into the sump. It will reach an equilibrium as long as your pump(s) doesn't pump more water than can physically flow through your intake plumbing. If your pump(s) can move more water than your plumbing allows, your intelligently designed sump has an inline valve that you can use to decrease the return flow thus maintaining a happy balance.

If you lose power, water from the tank can only drain to the top of the overflow, which on my tank is approximately 1 1/4" from the top of my tank. You have to also take into consideration that the return lines also become siphons if they are under water. The return nozzles sit another 1" below the top of the overflow in my tank, which means my water level drops 2 1/4" inches when pumps are off. In the 180, that's roughly 20 gallons of water that will flow back into the sump. As long as I never have more than a maximum of ~29 gallons of water in the sump while running, it won't overflow if I lose power.

When the tank is running, the water level in the tank will always be the same. The water level in the sump will rise and fall as water evaporates and when you top it off.

*note - This is assuming that you have a drilled tank. A siphon hang on overflow box does require additional considerations.

Thanks!

Feel free to chime in.........

Keep in mind this thread is really to help educate people like me who have never used a sump before. I might not ever set up one, but interesting to understand them all the same........

Scott.
 

pat w

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For hang on overflows (when they are adjustable in height) start with a dry sump and fill the tank to the highest level you're comfortable with. Set the overflow for the highest level it will go and start the siphon. Watch the level in the sump and be ready to break the siphon (note the return pump is off so there is nothing in the return line to siphon at this point). You should see the water drop below the lip of the overflow before the sump fills. Slowly lower the overflow a little at a time abnd allow the flow to stop, watching the level in the sump. When it reaches the acceptable level you have the lowest your overflow can be set safely. Start the pump and check the level in the tank, if it's not high enough raise the overflow but note somehow where the safe level is. When all is set mark the sump level for max fill during operation as a additional safety in the event you need to top off. As for the return line(s), make a small hole or two near the waterline (above or below, be sure to get them all). When the pump goes down and the returns start to siphon, as soon as the water drops below the hole(s) they'll take in air and should break the siphon

Pat
 

scottward

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Oct 26, 2007
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Fantastic info! Much appreciated.

Wait for it.........

I think I get it! ;)

A couple of questions:

1. In terms of the return pump - I guess you choose a pump that has no hope of returning the water back to the tank faster than water can come into the sump? This ensures that the pump will always be surrounded by water when it is on? So having a ball valve throttling the output is good here? Or, select a pump that when running flat out just isn't powerful enough? Obvious questions again, I think I already know the answer, just checking....

2. Instead of a siphon break, could a large non-return valve be used here? Hmmm. Non-return valve might fail (i.e. get clogged up), resulting in a slow but nevertheless siphoning of the tank? That siphon break hole could get something stuck in it I suppose. Several siphon break holes better??

3. CO2 loss - I don't get how you can maximise O2 in the bio media in the sump and also retain CO2. I believe you can cover the sump to prevent CO2 escaping but this would be counter-productive wouldn't it?????? If you cover the sump to prevent CO2 escaping, your also preventing O2 entering.........? This I do not get!

Scott.
 

Jim Miller

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Scott

I'm following the thread as well. I'm also interested in sumps.

I'm very biased in the "failsafe" direction due to huge water induced probs with this house and our tank location on carpet and hardwood floors. For me that would rule out any HOB OF I've seen so far.

But I've got an open mind.

Jim
 

tjbuege

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Ok, basic question... Is there a difference between wet/dry filters and sumps? Or are they two terms describing the same thing.

Thanks for that link Jim, starting to read it now. Looks interesting. One thing I don't like, though, is a ton of stuff hanging off the back of the tank. I'm moving to rimless to achieve a clean look. Been considering canister filter, but wet/dry / sump caught my attention. But the whole overflow thing has me questioning if I want to go that route.
 

RukoTheWonderDog

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Check out this website - keep in mind it is directed at Saltwater, so things like skimmers, refugiums, calcium reactors, etc. can be ignored. This guy has a great explanation of how things work, considerations, and caveats.

***disclaimer*** I am not condoning the products offered by this guy. I have not/do not plan to buy anything from his website, and have no experience with his sumps or other items for sale.

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

You are going to want to calculate your gph/lph before buying your equipment. For example - a 1" diameter tube can support roughly 600 gph flow, minus loss from any bends and other pumping pieces you have in place (elbows and other pieces will slightly decrease your flow). You then buy a pump(s) that is close to the numbers your system can support.

This isn't an exact science; you can always throttle back your pump if it is out performing the rest of your system.

There are many flow and sump calculators online that can help you with this task (most of them are aimed at saltwater, but that shouldn't matter here)

A freshwater sump is going to be only slightly different; we use a collection of filter media instead of a DSB and live rock (although they really provide the same end result).

A wet/dry system simply means that you have filter media that is not submersed in water but instead is drizzled/sprayed/dripped with water. This media stays wet and receives highly oxygenated water that grows more bacteria and breaks down more ammonia & nitrite than normal submersed media. A wet dry system can be accomplished in many ways - some guys add a powerhead or pump and use the output to spray water over the media chamber, others use a drip plate, and some people even dump the water directly into the media chamber from the tank (this creates problems with mechanical filtering however and tends to muck up the media with organic matter and cause nitrate spikes, fouled water, and algae blooms). I prefer the drip plate design myself; it doesn't require an additional pump (which reduces electricity consumption and eliminates a point of failure) and doesn't subtract from the return pump flow.

Biolante said this well before - the use of a sump is a trade off concerning CO2 levels. CO2 loss is more of a problem here than compared to a canister because it is an open system. The water falling in the overflow tubes to the sump gets mixed with air as does the water that gets dripped or sprayed in the wet/dry area. Any agitation of the water will cause dissolved CO2 to fall out of dissolution in an open system. Even if you seal the sump, it's not going to be 100% air tight and will still have plenty of O2 entering the system from the overflows. Having the sump sealed simply means that CO2 levels in the sump are going to be much higher, so agitation at this point will be in an environment where the CO2 is high and some gas will dissolve back into the water.

I inject the CO2 into the return pumps, which means that the water returned to the tank is rich in CO2. Since the overflows take most of the water from the upper part of the water column (this is dependent on overflow design) the CO2 in the lower parts of the tank where the plants need it is at a good level. I have my return jets aimed at the substrate, and it seems to work pretty well.
 
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shoggoth43

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http://reefkeeping.com/issues/2003-01/gt/index.php

Keep your splashing to a minimum. Seal the biotower. Sump and wet/dry are not the same. You can have a sump without a wet/dry but the wet/dry is usually located in the sump. Gentle and minimal drops are helpful. Herbie/bean style overflows will work better in terms of out gassing as you aren't injecting lots of air into the sump with the overflow compared with a gurling standpipe or durso/hofer style. Noise will be less of a concern as will bubbles as well. All things the same, you will have fewer issues with a bulkhead in the back of the tank and overflow box compared to a siphon style overflow as well as a larger throughput.

I think George Booth and Tom has some data on just how "bad" the outgassing is and it doesn't seem to be nearly as significant an issue with a wet/dry as it's made out to be. Outgassing is not necessarily a bad thing. Yes, you will need to add more CO2. However, as you will outgas quicker you will have a safety net against gassing your fish and won't have extremely low O2 at night when the CO2 is off. Some of Tom's posts suggest that higher O2 and possibly flow as well have an effect on minimizing algae. I don't think there's a consensus on this but there's anecdotal support for this.

-
S
 

pat w

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tjbuege;73453 said:
I could use a good description on how a siphon break is implemented and how it works.

Anyone who has ever tried to keep a siphon going knows the worst thing that can happen is to get air in there. Enough air and the siphon just quits. An intentional siphon break uses this to the users advantage. When the pump is running the return line is full of water under pressure being returned to the tank. As stated when the pump quits that line full of water acts as a siphon back down to the sump. It will continue to pull water through the spraybar, nozzle, whatever as long as no opening is exposed to air. Once this happens the siphon sucks in the air and the game's up; no more siphon and the remaining water in the back side of the line falls to the sump untill the entire return line is full of air. The "Siphon Break" uses an extra hole to intentionally make this happen as soon as possible after the pump quits. The added hole (or holes) are drilled at locations that place them near the water line so that either imediately after the pump quits or very soon thereafter, this hole is exposed to the open air and "Breaks the Siphon". While the pump is running the extra hole is just one more place the returning water can exit.

tjbuege;73455 said:
Thank you, this makes sense. So I suppose you could say the bio wheel on my power filter is "wet/dry" since it's open to the air?

Yup, the occasional exposure to air increases the available O2 and increases the effectivness of the bio-filter.

Pat
 

tjbuege

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Ok, I believe this stuff is starting to make sense. Still some questions, though. I understand a siphon break in terms of the return line. But what about with an HOB overflow box? If that overflow siphon "breaks", water will stop flowing into the overflow, and will eventually flow over the top of the tank. Yes, I could simply run with a lower water level in the tank to that tank water + sump water < tank capacity. But doesn't that negate one of the benefits of a sump, namely having increased capacity? What to do if the overflow siphon stops working?

One of my goals is to minimize "stuff" in or on the tank. One reason I decided to go rimless. I was also considering a canister filter setup, which is a clean look. If I go the sump route, I'll need an overflow box hanging on the tank (I don't want to drill my tank). How small can they be, and still be effective? My tank size will be 50g (36x18x18).

How big of a sump is needed? In my example, with a 50g tank, would a 10g sump be big enough? I'm thinking DIY to save $$$ and 10g tanks are cheap.

Do the overflow lines and return lines need to be rigid? I don't fancy the idea of ugly white PVC. Something clear would be far better.

The posts so far have been EXTREMELY helpful, so thank you very much for sharing your knowledge. I've also been reading those links you all have posted, and following more links contained within. There's some very helpful web articles... thank you that info. I really am starting to get my brain around this. It isn't quite so mysterious anymore. I'm eager to try it out! :)
 

pat w

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Yes, in your case an OF box would be required. If tank clutter is a heavy issue you may be better served with a canister and glass pipe sets (glass over the rim siphon tubes and Lilly Pipe returns). They will give you the clean look you want. I personally would never run a sump without a top skimming OF of some sort. The danger of a flood during a power loss would be too great unless the sump was quite large in comparison to the tank.

Pat
 

tjbuege

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Not sure I intended to imply clutter was a "heavy issue"... :) And I do have other tanks, so I'd still like to consider sumps. I do understand the need for an overflow box, whether built in or HOB. So what about my other questions? Your answers have been very helpful so far, keep 'em coming! :D
 

chopsticks

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One advantage of a wet/dry is the huge amount of media you can put in it. I have a DIY wet/dry filter for my 70gal tank and it has about 2.5 – 3x the media that you can have on a Fluval FX5.
 

Jim Miller

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I like the idea of the sump. If I was in a position to make my tank location "permanent" I'd probably use one with a coast to coast OF either internal or external and a Beananimal system.

It looks especially attractive above 120g or so since multiple canister filters of sufficient size get really pricey.

But for my 90g I'm satisified with the bottom drilled option I chose and a canister with an auxiliary CL pump circuit.

Jim
 

pat w

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@Tim - I'll try to help all I can. In your case for every inch of water level drop in the tank the level in the 10g sump would raise about 3.25 inches so if you could live with the water level in the tank at about 2" - 2.5" from the top that would put plenty of water to cover the return pump which is of course a major concern. I see no reason that a 10g sump wouldn't work for you. Also remember the fiter media that is submerged displaces some of that water so that would raise the water level in the sump even further. The overflow lines need to be free flowing. If you can find some high quality clear vinyl hose that won't kink that'll be about the best you can do do avoid the white PVC. Straight shot from the OF to the sump will yield the best in terms of flow volume. Over sizing the hose and needed fittings by one size is a plus there too.

Noise abatement is something to think about. Gurgling OF's and noisy sumps can be rough on the nerves. Google some of the following and read up.

Stockman overflow/ stockman standpipe
Durso overflow / Durso standpipe
Hofer gurgle buster
Herbie standpipe
Beananimal

Also look around for for info regarding quieting or silencing the sump itself as there are noise concerns there as well. Most are involved with freeing trapped air from the siphon line.

I'm working on a new drop-in sump insert for a 10g I bought at Walmart. It'll hold a 5.3/4" x 5.1/2" x 4" mech sponge + an additional mech pad over a bio media chamber that will hold nearly 4 liters (I use Matrix and 4 liters is spec'ed out to handle up to 400g so my 90g should be no problem). All of this takes up around 3.7g of space on one side of the tank. I should have no trouble running my 90 with this but it goes against the conventional wisdom on the subject so I'll just have to build it and see.

Pat
 
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tjbuege

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Thanks Pat. I've been doing a lot of reading. There's some very helpful articles on some reef sites that explain sump operations.

Your answer brings to mind a basic question: What's a typical water level in the main aquarium that uses a sump? I've been picturing something like 1" below the rim, but I'm beginning to realize that's probably not practical or safe. Also, how much water is typical in the sump itself (under normal operation)? Not full, of course. Half full? Maybe it depends on dividers and chambers?

Regarding water drop, if the siphon-break hole(s) in the return line is placed just under the surface, then there really shouldn't be much water drop, right? I figure for a 36x18 tank like the one I am planning, 1/2" would be about 1.5 gallons, 1/4" is about 3/4 gallons. So I would only have to account for that, plus the volume of water in the return line and overflow pipe?

The overflow box sounds like it's potentially the weakest point in the system. The potential of losing the overflow siphon (bubbles getting trapped/collecting in the siphon tube for example), junk from the tank clogging the overflow, etc. How are these things avoided or reduced? That's the sort of thing I need to figure out and plan for. I've also read some about silencing the overflow pipe. Some ideas can be complicated.

I understand the potential disasterous consequences of breaking the siphon in the overflow box: water pumps into the aquarium, but has nowhere to go but up...and over the edge of the tank! So, water will pump in as long as the return pump in the sump has a supply of water. Pretty basic stuff. I did notice many sumps have the return pump in a separate compartment in the sump, so if the overflow siphon breaks, the pump will only empty the contents of that compartment, not the entire pump. Is this a good design? Or does it have problems? I figure if that compartment holds 2 1/2 gallons max, then I can maintain my aquarium waterlevel at 1" below the rim.

I saw a good explaination of all this (sorry, can't recall the link right now). One person suggested that the pump doesn't have to sit on the bottom of the sump, but could be elevated some amount. This would also reduce the potential amount of water pumped into the aquarium should the return siphon break. Is this a good idea? Are there reasons to have the pump on the bottom of the sump (or pulling water from the bottom if it's an external pump)?

One thing I don't like is the cost of commercial overflow boxes. Rediculous prices for a bunch of plastic. Not sure i'm up to a DIY project, though. Not my first time with a sump. What are good brands? I've seen references to CPR, Eshoppes, Tom Aquatics, Lifereef (this one seems to get the highest praise from reefer forums).

Again, thanks for your patience, I know my questions are many, and a bit scattered. It's hard to organize my thoughts when my mind is racing with ideas and questions. That happens when I go on a reading frenzy, trying to soak it all in. :) I will be sure to research those "gurgle busters" and "silencers".

Make sure to share with us your experience with your DIY sump. Sounds interesting. What I should probably do myself is just setup a sump for my 20 gal tank. A 10 gal aquarium would be more than big enough for that. And it would be a good learning tool. I'll have to think about this some more.