What are overflows?
- Thread starter pzuzu
- Start date
I use an overflow on my 150gal tank, which is freshwater. There are two types of overflows: those that hang on the back of the tank, and those that utilize holes drilled in the tank, either in the bottom or the back. I have a HOB overflow bow on my 150 freshwater, and my 55 sw tank is drilled in the bottom.
The basic premise is that you have the tank, and a sump underneath it with a pump. If the pump is off and you add water to the tank, the tank overflows and drains down a tube or pipe into the sump. It is not a syphon, so when the tank level gets low enough again, it stops overflowing and everything is static. So, when you turn the pump on, it pumps water up from the sump into the tank. The water level begins to rise in the tank, and starts overflowing via the overflow mechanism (box/drilled holes). After a few minutes the tank reaches an equilibrium where the water level shouldn't change as long as the pump is running and the overflow is flowing freely.
Typical in-tank overflow system (required drilled tank) - these generally have a box built around them to help hide the plumbing. One pipe is the overflow into the sump, the other is the return.
Diagram of typical HOB overflow box
Picture
My homemade overflows. Effective but noisy.
The basic premise is that you have the tank, and a sump underneath it with a pump. If the pump is off and you add water to the tank, the tank overflows and drains down a tube or pipe into the sump. It is not a syphon, so when the tank level gets low enough again, it stops overflowing and everything is static. So, when you turn the pump on, it pumps water up from the sump into the tank. The water level begins to rise in the tank, and starts overflowing via the overflow mechanism (box/drilled holes). After a few minutes the tank reaches an equilibrium where the water level shouldn't change as long as the pump is running and the overflow is flowing freely.
Typical in-tank overflow system (required drilled tank) - these generally have a box built around them to help hide the plumbing. One pipe is the overflow into the sump, the other is the return.
Diagram of typical HOB overflow box
Picture
My homemade overflows. Effective but noisy.
Thank you sploke for the info...but I'm still unclear as to what purpose they serve. Could you clarify this? I think I understand now how they work...but not sure as to the purpose. Is it just added filtering? Is it for mixing chemicals or salt? Is it for added currents? Is it for having more water than the tank itself allows to have more of a bioload?
And what is a good estimated price for a used 125g tank with a drilled overflow?
Somebody in my town has one and they just want an offer made.
Thanks for any extra info!
And what is a good estimated price for a used 125g tank with a drilled overflow?
Somebody in my town has one and they just want an offer made.
Thanks for any extra info!
The point is to move water from the tank to the filter. I have a 150gal tank, and a sump underneath the tank. The sump has a wet-dry filter in it. By using an overflow, it allows be to put all the filtration and heating equipment in the sump instead of in the tank. the overflow itself is just a mechanism to get water out of the tank and into the filter, by means of gravity.
Without an overflow, I would either have to use massive HOB filters or several canister filters on the tank. I chose to save lots of money and build my own sump for a giant wet/dry filter. The overflow allows me to get water from inside the tank to down into the filter.
Without an overflow, I would either have to use massive HOB filters or several canister filters on the tank. I chose to save lots of money and build my own sump for a giant wet/dry filter. The overflow allows me to get water from inside the tank to down into the filter.
So if I were to purchase a used 125g tank with a drilled overflow system and a pump with a stand described as not being very pleasing to the eye but gets the job done, any suggestions on what my offer should be? This is probably a tough question, but any help would be appreciated. Also, anything else I should ask about? I found the tank online right in my small town and this might just be the kind of tank I've been waiting for without buying brand new.
Also, is there another advantage to overflows other than hiding the equipment? I've see a few cannister filters made for tanks even larger than this at drsfostersmith.com. Are those cannister filters just extremely huge?
Sorry I have so many questions, but I'm just wondering if I want this tank or if I would rather just stick with what I know and wait for a tank that hasn't been drilled. I'm very familiar with cannister filters...just never even seen an overflow...so...completely and totally ingnorant here.
Also, is there another advantage to overflows other than hiding the equipment? I've see a few cannister filters made for tanks even larger than this at drsfostersmith.com. Are those cannister filters just extremely huge?
Sorry I have so many questions, but I'm just wondering if I want this tank or if I would rather just stick with what I know and wait for a tank that hasn't been drilled. I'm very familiar with cannister filters...just never even seen an overflow...so...completely and totally ingnorant here.
I use a 500gph aquarium pump to get the water from the sump back up into the tank.
The advantage to using the sump over a canister is that, including the cost of the pump, I built the wet/dry filter and sump for probably about $150. I would have to spend probably close to $400-500 on canisters to get equivalent filtration.
For a 125gal drilled tank with a not-so-nice stand and a pump, and nothing else, I would probably offer around $150 and see what the guy selling it says. A lot of it depends on the tank condition, and what accessories come with it. Are you positively sure its not going to leak? Are there any scratches in the glass or cracks in the plastic frames? Does it come with the bulkhead fittings and plumbing for the overflow setup?
The advantage to using the sump over a canister is that, including the cost of the pump, I built the wet/dry filter and sump for probably about $150. I would have to spend probably close to $400-500 on canisters to get equivalent filtration.
For a 125gal drilled tank with a not-so-nice stand and a pump, and nothing else, I would probably offer around $150 and see what the guy selling it says. A lot of it depends on the tank condition, and what accessories come with it. Are you positively sure its not going to leak? Are there any scratches in the glass or cracks in the plastic frames? Does it come with the bulkhead fittings and plumbing for the overflow setup?
Thanks sploke! I'll ask him all of those questions right now...and even quote him that price. That's just what I needed!
As for cannister filters...if I get this tank I guess I won't need one...but just out of curiousity, if you have time, if you go to drsfostersmith.com and type in 910098 in the search box, what would be wrong with this filter for 125g tank? It says its for up to 159g with an output of 264gph for $101.99. I figure if I don't get this tank, I might still try to get a tank about this size, primarily for discus.
Thanks for all the info!
As for cannister filters...if I get this tank I guess I won't need one...but just out of curiousity, if you have time, if you go to drsfostersmith.com and type in 910098 in the search box, what would be wrong with this filter for 125g tank? It says its for up to 159g with an output of 264gph for $101.99. I figure if I don't get this tank, I might still try to get a tank about this size, primarily for discus.
Thanks for all the info!
with a 125 you may have dead spots in the tank ,,debris will collect in these spots..I use powerheads with prefilters on them to move the water from the dead spots.
I currently have a 75 with a 1140 gph rating..tho I doubt it is putting that much out. my 125 will have a 1540 gph with 3/4" feed to the tank and 1 1/2" drain.
just some food for thought.
I currently have a 75 with a 1140 gph rating..tho I doubt it is putting that much out. my 125 will have a 1540 gph with 3/4" feed to the tank and 1 1/2" drain.
just some food for thought.
Advantages:
1) you can hide all equipment in the sump tank
2) because of #1 you dont have any wires/hoses going up behind your tank
3) extra water volume in your tank, you could easily build a sump that holds an extra 25-50 gallons of water or more.
4) you could make a refugium in the sump, you could put fry in there or snails, etc.
5) the water level in your tank will always remain full. evaporation will show in the sump tank - the water level in your sump will go down but not in your main tank
6) you can add medication, chemicals, fertilizers, whatever to the sump, without having to get into you main tank
7) you could plumb a drain line in for easy draining of you tank for water changes.
8) easier to alter the design later for your needs
9) allows you to do an open top tank without a bunch of stuff visible for those interested in open tops.
probably more, its late and I am tired.
