Freshwater Sump

[myenigmaself]

Howdy,

It looks like in the near future I'm going to be the proud owner of a new setup. 55 Gallon main tank with a custom stand holding a 29 Gallon below. I see this as the perfect opportunity to set up my first sump. My first question is the big one:

Should I really create a sump for a freshwater tank?

I've looked all over the place and I've found varied opinions as to whether or not this is a good idea for a non-marine system. Most people say it's overkill. Some say it causes problems with CO2 and you'll need injection for your plants. I'll break down the pro's-con's I can think of below:

PROs:
Increases the biological footprint of the system, making it more stable.
Better for introducing chemicals.
Better/easier to perform water changes.
More attractive, as you can hide your heaters in the sump.
Allows you to add plants to non-plant-friendly tanks.
I plan on eliminating active filtration, which would remove the complexity and cost of 4 filters (2 for each tank).
I would think it would be pretty easy to setup the second tank as a breeder if need be.
It's cool since it's something I've never done before.

CONs:
It can cost more, depending on how complex the system is.
It's a little more risky.
It essentially negates any CO2 injection.


I think the PROs out-weigh the CONs: especially the last PRO. My question to the community is did I miss anything?

My thoughts on setup are as follows:
Main tank (55g) I plan on housing a decent sized community (6 or so, I need to see the tank before I decide on the number) of dwarf puffers and kuhli loaches (a combination I've had success with in the past, but the loaches have a tendency to dig up plants). If I can find a small algae eater I'll add it, but if not probably an otto. Sand substrate. No plants. Lots of driftwood to break up lines of sight. Rather than drilling I would like to create an overflow, much like the one found at melevsreef.

Sump (29g) Broken into two sections, one main section taking about 80% of the tank, and the other section just to house the pump. I'll get into that a little more later. As for inhabitants, various invertebrate and a plethora of plants. Most likely a gravel substrate, possibly infused with some fine sand as a base.

The reason for splitting the sump is two-fold. I plan on screening the flow from the main section to the pump to make sure all effluent/food-scrap remains in the sump to feed the invertebrates and plants. Additionally, I would like to minimize the amount of water available to the pump so if my overflow on the main tank somehow becomes un-primed or clogged my pump will only push up a few gallons (not the entire 20+ gallons) and hopefully I will avoid an overflow in the main tank. I will probably burn out the pump (if this happens) but I'd rather do that than flood my house. To this effect, is there a better way to prevent an overflow in the main tank? Maybe a water-level based shutoff of sorts, much like that found in a toilet only reversed?


So in short, is a freshwater sump a good idea, particularly in my scenario, and are there any safety measures that can be taken to prevent overflow in the main tank in the event my overflow gets air in it or the outflow becomes clogged?

 

[rabbut]

The best way to prevent the main tank flooding, is to drill the tank. Overflow boxes are notorious for going wrong should the power fail Drilling is actually safer and cheaper than an overflow box, and the only way that I would consider doing a sump myself

IMO, sumps can be one of the best filtration methods available, but just how effective they are depends on how you set them up. In FW, you want most of the tank dedicated to bio-media in a trickle filter. This is most efficient in terms of filtration. You need the pump area to take at least 20% of the main tank's volume, or the sump will overflow in the event of a power failure, assuming you have enough water in to cover the pump when running... This means to you that you will probibly have to have the pump at the bottom of the sump and the media over the top.

All the best
rabbut

 

[myenigmaself]

What if I drill and the overflow hole gets clogged, or is that just best prevented by using some sort of screen/sponge to prevent things from getting in there? And from what you're saying it sounds like I should be splitting into three sections: pump reservoir, refugium, and a section devoted to bio-media. I definitely want to have a refugium to house plant-life and raise some treats for the puffers. I don't think 3 secions will be a problem since the sump will be well over half the size of the main tank. Thanks for the input!

 

[rabbut]

Reforgiums aren't usualy used in FW, but if you want one, don't let me stop you, they are great nitrAte sinks

Usualy, when you drill, you fit a Calfo overflow to the tank. This uses two holes, one in the base, the other in the back. You fit a Duroso standpipe to the bottom hole (inside a weir, out of sight) and have a valve fitted to that line to limit flow to just less than that of the pump. A small amount, just not quite enough to start a syphen, then goes down the hole in the back. If the main drain blocks, the one in the back takes over and becomes noisy, alerting you to the problem

 

[myenigmaself]

Thanks Rabbut! Do you see any problems drilling in the bottom of the back of the tank instead of in the bottom itself (it's tempered, and my understanding is drilling tempered glass is a no-no. I'm nervous about drilling at all, but I do agree that it's a much better solution than trying to use a siphon). I'm sure I could whip together a DIY weir and plumb it all together no problem. I didn't know that the weir solution employed two holes. It's much more attractive now. Thanks!

I also threw together some plans for the sump itself. I find the idea of a Refugium really attractive since it solves my plant problem and will hopefully allow me to only have to setup one more 10G to breed snails. It will make my girlfriend happy too as she wanted some sort of shrimp that I can't keep with the puffers (even if they eventually become food).

I attached my sump plans. I may limit the bio-media to a corner (keeping the same volume, just shifting it around to make the sump a little more attractive). Thanks again for the great advice!

 

[myenigmaself]

To add more food for thought I came across the idea of a horizontal overflow. This requires the drilling of one more hole, and seems a tad bit more complicated (nothing crazy though), but has two fail-safe's and kind of makes sense since I can't drill the bottom of my tank. Any thoughts on this?

Also, any idea what a glass shop would charge to drill holes in the back of an aquarium? It looks like a 1" hole bit is going to cost close to $50, so I wonder if DIY is worth it.

Thanks!

 

[rabbut]

Glass shops probibly won't do a tank. The best bet would be to find a local Reef club and ask the members. It's a regular request for them

The horizontal overflow looks workable, but I personally prefur Calfo+Weir set-ups. The final choice would obviously be your's The sump lay-out looks fine

All the best
Rabbut

 

[myenigmaself]

Thanks again for the advice rabbut! I think I've got enough direction to start running. I'll start another thread to document my progress once I have the tank in hand

 

[myenigmaself]

One last question:

I've found a local glass shop that will drill my tank and also sells acrylic. He gave me the following options: "we can provide you with plexi thickness of .100; 1/8 and 1/4 inch or Lexan thickness of 1/8 or 1/4 inch."

My understanding is that plexiglass is acrylic, while lexan is the more expensive and stronger big brother of acrylic. What I want here is the plexiglass (just a brand name of acrylic) and I'm thinking 1/8" should do the trick. Am I right there?

 

[smegforbrains]

If your tank is made from tempered (toughened) glass, you cannot drill it at all - it will shatter instantly! It would be highly unlikely that only the base would be tempered.

Tempered glass is essentially there for safety. It shatters into tiny fragments so that you cannot slice yourself open if you tread on or fall through it.

If it is made from tempered glass, there should be standards mark etched into it. In the UK it will be a BSI kitemark but I am not sure of the USA alternative.


BTW, what do you want the plexiglass for?

If it's for dividers, you may just as well use 4mm float glass siliconed into place, it will be cheaper and more scratch resistant.

 

[myenigmaself]

Hi smegforbrains,

I thought it was pretty common for just the bottom of the tank to use tempered glass, where the rest of the aquarium is non-tempered, due to the added strength and scratch resistance of tempered glass. The common exception being bowfronts. I'll check it out when I get it, but I was told by the current owner that only the bottom is tempered. I also found this reference, stating that a 55 regular has a tempered bottom (although I would imagine that's manufacturer specific). Thanks for the warning though.

As for the acrylic, I was using it primarily because that's what everyone else who's done this seems to have used. I don't really know anything about float glass, but thought the structural properties of acrylic would be a good fit, particularly since the divider between the refugium and the pump will be slightly load bearing (I expect that the level of water in the pump reservoir will be lower than that of the rest of the tank).

Thanks a bunch for your input! If my quote for the acrylic is crazy I'll definitely look into float glass.

 

[rabbut]

I would use glass for all load-bearing dividers, such as the one between the reforgium and pump, as you cannot glue glass to plastic/acrylic. If you try to, it will give way under pressure, obviously something to be avoided. The tickness of glass you require depends on the deapth of water at one side of the pane. 4mm should be OK for a pro to glue for you upto 15" deapth, but if you are doing it yourself, 6mm will be easier to glue, due to increased glueing surface area

Acrylic will be fine for the media-reforgium divide though, as that should not be taking too much pressure

All the best
Rabbut

 

[myenigmaself]

Will the glass be more or less expensive than acrylic? And I'll just be "gluing" it with aquarium safe silicone sealant, right?

 

[rabbut]

Will the glass be more or less expensive than acrylic? And I'll just be "gluing" it with aquarium safe silicone sealant, right?

Glass should be about the same price for Float of equivelant thickness, or a tad cheaper, depending on the glass supplyer and time Yes, Aquarium Safe silicone for gluing

All the best
Rabbut

 

[myenigmaself]

Cool! I'll see if the supplier has it available I'm assuming it's going to be cheaper for me to get all my pieces in one medium. There shouldn't be any issue building my 10"x4"x4" internal overflow box out of it too, should there (I decided to go with the horizontal overflow, just trimmed down a bit)?

I should just say thank you in my signature