pumps 101

[400M1963]

read june and prior issues. i want to hard plumb a 75 gallon all glass brand on garden variety LFS pine stand. how do i go about plumbing this? should i use a 20 gal high tank for sump and also, which external pump to use? thanks for good advise. feel free to get remedial

 

[rexn]

I need some additional information before I can make any recommendations on your proposed system.

Do you have a built in overflow in your tank? This makes things much easier if you do, if not, are you willing to drill your tank to accommodate overflow (likely should be done by experienced hand at drilling glass)?

What kind of tank will this be, fish or reef?

Will back of tank have to be flush with wall or can it stand out some (< 6")?

Are you willing to use internal circulation pumps for some of your circulation needs (i.e., in addition to sump pump)?

I assume sump will be under tank, does stand to be used have sufficiently sized openings to accommodate sump of desired size (your suggestion of a 20 gallon sump would work well for a tank this size)? How high is stand (remember that even if your sump fits under tank you need enough clearance at its top for maintainance and placing equipment such as heaters and/or submersible pumps if desired)? A taller stand gives more room for sumps/equipment underneath but may make cleaning tank somewhat more awkward.

Regards, RN

 

[400M1963]

I need some additional information before I can make any recommendations on your proposed system.

Do you have a built in overflow in your tank? This makes things much easier if you do, if not, are you willing to drill your tank to accommodate overflow (likely should be done by experienced hand at drilling glass)?

i don't have a built-in overflow but i specifically purchased a tank that is drillable. over a year later, that now seems to point to a hassle getting it drilled. but there's an experienced LFS who has bulkheads located on top rear of their tanks and he drills tanks for patrons.

What kind of tank will this be, fish or reef? Will back of tank have to be flush with wall or can it stand out some (< 6")? Are you willing to use internal circulation pumps for some of your circulation needs (i.e., in addition to sump pump)?

my tank is a 1 & 1/2 years old reef with 90 lbs. LR and 4" DSB, set up with remora pro hot skimmer and several maxijet 1200 powerheads. i could possibly put the LR and tank water into rubbermaid trash cans and transport the tank to LFS with DSB intact in small amount of water. also, rather than try to convert i guess i *could* consider getting a new reef ready allglass to occupy the present stand - it currently sits out from wall about 6". i would like to use one or more external pumps in order to be freer from heat concerns, unless it's not feasable. if need be, i would keep internal powerheads.

I assume sump will be under tank, does stand to be used have sufficiently sized openings to accommodate sump of desired size (your suggestion of a 20 gallon sump would work well for a tank this size)? How high is stand (remember that even if your sump fits under tank you need enough clearance at its top for maintainance and placing equipment such as heaters and/or submersible pumps if desired)? A taller stand gives more room for sumps/equipment underneath but may make cleaning tank somewhat more awkward.)?

Regards, RN

this is the allglass-brand pine stand made to fit the 75 gallon tank, nothing special. there are two standard openings each on both front and back of 15" x 21" with doors fitted on front openings only; the rear openings are used for acccess inside. the stand is 28" tall and the recessed area underneath the tank spans 46" that equipment sits in. at least apparently, the sump would need to be placed inside from the top of the stand. i'm primarily interested in getting a sump to increase water volume. the external pump would not necessarily have to sit inside the stand but it would be nice if it did. of course a quiet and efficient pump or pumps are valued. let me know what you think.

 

[rexn]

Did not originally realize your where modifying an existing tank, makes things somewhat more complicated but manageable. I would still recommend that you arrange to have the tank drilled for an overflow. You can try to use a hang on overflow but I'm not a big fan of these since most use siphons to transfer water from tank and I've found these to be unreliable or at best requiring more maintenance than I like.

Probably the simplest overflow would be a bulkhead fitting located near the top of the tank somewhere and then plumbed back to the sump. You could also place a bulkhead on the tank bottom and fit with a stand pipe but is more risky should you have any leaks but does have the advantage of not requiring any externally visible plumbing. In either case I would use at least a 1" diameter bulk head fitting to assure this does not limit your flow rate from your sump. If in the case of the top located over flow this results in a tank level lower than you wish for your flow rate you can insert an elbow fitting in the overflow inside and then adjust the tank level by changing its rotation angle. You may also need to place some sort of strainer on the input of overflow to keep smaller specimens from getting suck in. Do not make strainer too fine or it may too easily clog, unless you have very small fish would make strainer with not less than 1/4" holes.

It sounds as though you have the sump issue under control and that your stand will accommodate this OK. I was not sure whether your sump was to be glass or acrylic? If glass then you have the same potential issue as main tank if you wish to use external sump pumps in that I would recommend you have it drilled for bulk head fitting(s) somewhere near the sump bottom at one end to locate external sump pump(s). You can try to use pipe to go over top of sump to feed pump(s) but this is more problematic in terms of priming pumps and may create problems if you have power failures unless you use check valves to keep help keep water in these pipes to keep pump(s) primed. Obviously submersible pumps would be the simplest solution here from a plumbing perspective but as you pointed out will result in more heating of tank.

As to actual flow rate suggestions, I like to see at least 5X turn over rate per hour in a tank (combined sump and internal circulation pumps) though this will depend on the type of specimens you are keeping. If you plan to keep SPS corals you may wish to significantly increase this. If we assume that accounting for your rock and sump that you have a total of 70 gallons of water this means a net flow rate of about 350-400 gal/hr. If we use worse case of using just sump pumps and assume you are pumping into a height of say 4' and then add an additional 3' of head due to plumbing losses we get a net requirement of about 400 gal/hr into a total head of 7'.

Total flow rate as I stressed in my articles is only half the battle, quality of circulation in the tank is equally important. By quality I normally mean that you avoid stagnant circulation patterns in the tank. To do this you normally have to be able to randomize the flow patterns by some means. Using multiple returns helps in this but to really randomize the flow patterns you need to use either a wavemaker/timer and/or oscillating returns of some sort.

In your case you can go several ways, if you are really concerned with heat build up in your tank and want to stay with external pumps then you can use 2-3 external pumps operating on timers or wavemakers or alternately use fewer pumps but use oscillating nossels such as Sea Swirls or similar units. If you are willing to use some supplementary internal circulation pumps then you can place these on timers and use a smaller sump pump(s) (still try for at least 2-3X turn over rate for the sump pump to allow proper operation of any sump filters or heaters).

One last comment concerning your heat worries - while an external pump will dump less heat into a tank than an equivalent submersible pump it still adds heat and pumping from your sump will require a corresponding larger pump due to the elevation requirements whereas an internal circulation pump can be made smaller for the same flow rate due to little head requirement. You may find that use of a few smaller internal circulation pumps in conjunction with smaller sump pumps will be just as cool as external sump pumps alone. If you are really concerned with heating tank from pumps then use an external circulation pump (takes water from one location in tank and pumps out at another) in conjunction with a smaller sump pump (obviously more complex concerning the plumbing requirements - no free lunch).

Having said all this (I know I'm a bit long winded) I would recommend you keep your internal circulation pumps (I assume you have at least 2-3 of these) and put them on timers/wave makers and then add a smaller external sump pump capable of say 300 gal/hr @ 7' head. Assuming the pump has at least a 12-14' head capability this means a pump of probably 600-800 gal/hr rating. For increased reliability you could use two sump pumps either rated at half the flow rate each or you could also use timers on two larger pumps to further help randomize the flow patterns in your tank even more (again more work to plumb but the added piece of mind may make it worth the additional effort and expense).

I'm not going to make a specific recommendation concerning pump make as I do not have a lot of personal experience with many pumps in this rating range (mainly smaller and larger) but there are many models available so you should have little problem finding one that meets these requirements.

Hope this helps, RN

 

[400M1963]

great information (printing it as we speak) and you covered many areas that i've been considering. i am closer to tackling this plumbing stuff.