Need some help to get my tank going!!!

[the Wizard]

Hi Guys,

I'm new here but excited about joining. Haven't done any salt water in 20 years and things have changed a lot. I need some help.

I'm setting up a 185 gallon acrylic tank built into the wall of the den of a house I just moved into. The tank has no capability for overflow and since it was mounted in the wall I didn't want to remove it to have it modified...however, I am pretty handy and can do most mods etc.

So I bought a CPR wet/dry/sump, an AquaC protein skimmer, and 2 mag 18 pumps. I built two acrylic overflows myself and plumbed the whole thing. Seems to work fine with one major problem....the siphons are no where near fast enough to be able to keep up with the mag 18 from the sump to the tank. I have 2 1" ID and 1 3/4" ID flex tubes for the siphons for each overflow. If my calculations are correct that gives me over 4 sq" of siphon area, but it seems to not be enough. Can anyone shed any light on my situation.

Thanks, Ross

 

[liquid]

Hi the Wizard and

How exactly do you have your overflows built? Did you use Durso or Stockman stand pipes? Any way you can get any pics or draw out how it looks?

Shane

 

[the Wizard]

Hey Shane,

Good idea on the pics....I'll do that tonight. But it's basically similar to what I've seen. Two acrlic boxes (each side), one inside the tank and one outside. The one outside has two chambers, one to accept the siphon, with a divider that sets the water level, and then just a bulkhead fitting on the other side (noise is not an issue). Then it's plumbed directly to the inlet on the CPR wet/dry. It seems as though it would work fine if the siphons would only flow fast enough. I'll do pics.

Thanks, Ross

 

[Anonymous]

heres everything you want to know and then some 8O

http://www.advancedaquarist.com/issues/ ... turejp.htm

but that is pretty freakin' technical.

so, i am gonna go out a limb here and say you have more pump than outflow.

a mag 18 is rated at 1800 gph and your combined 1 inch can only do maybe 1400 (?).

now maybe you say you have additional overflows other than the 1"? i read it as you have 1" that are piped with 1 3/4".

maybe one mag is running the skimmer?

BTW, if you only have two 1" overflows then you have less than 2" of siphon area.

 

[the Wizard]

Hey Podman,

Thanks...I'll check that site out...I can handle technical. I have one 3/4" pvc line from each overflow back to the wet/dry. But these are not running full capacity as the siphons can't keep up. My siphons were made of pvc but I dumped those because I couldn't see what was happening inside. At least temporarily I'm using two 1" flex hose and one 3/4" flex hose on each side....three hoses form the siphon for each box....6 total. Total area of 6 hoses are about 4 sq.in.

What do you think? Why can't these keep those two 3/4" pvc return lines full?

Ross

 

[Anonymous]

what is the outlet size on the overflow boxes?

that is your maximum capability, right?

 

[the Wizard]

Right....ultimately. Each overflow box has a 3/4" pvc outlet...but they are not running at full capacity because the siphons are too slow. This is even though there is much more siphon area....just not much force pushing the water through them though.

Ross

 

[Anonymous]

now you are sure that there is inadequate flow at the 3/4" outlet?

this may seem elementry but i need to cover all the bases. putting additional hoses on the same outlet will make it seem like a slow flowing outlet at the discharge end of the hose when it may well be screaming through the smaller 3/4" outlet.

so, to be persnickety, you actually have the same lesser amount of siphon area, you have just increased the amount of suction on that same outlet by increasing the total head pressure (suction) below it. did that help at all?

 

[the Wizard]

Podman,

First let me say thanks again for working through all this with me. I think I understood your post except for maybe a bit of the last paragraph, but let's see if this helps.

The CPR 3000 wet/dry has two inlets, so each overflow is plumbed directly to each port on the wet/dry. No Ts in either line. And the last foot or so into the wet/dry is clear flex line....so I can see each is running at 50% or less. I can also see the water going into the bulkhead fitting of the overflow box, and it just trickles down there. I mean there is a lot of water moving, but there is certainly no standing water above the overflow outlet bulkhead fitting. As water enters that side of the overflow box it immediately spills over the edge of the fitting.

Ross

 

[Anonymous]

then your problem is upstream of the 3/4" fitting.

these are a J tube setup?

 

[the Wizard]

I first used a U shaped pvc tube made with two 90s. But I couldn't see the amount of air trapped in them when I started the siphon. So I went to clear tubing as at least a temporary solution. This way I can be sure I have no air trapped in the siphon tube. So yes, I just bend them over into a big U shape from the box in the tank to the box outside the tank.

Another problem I can see down the road is that even after a fairly short period of time running they are already creating an air bubble due to the air in the water.

BTW, when I say U shape...that is because the inside and outside boxes are the same depth...so the tube has the same length on both sides...therefore a U rather than a J?

 

[Anonymous]

so these are DIY boxes, eh?

i think at least part of the problem here is you likely don't have enough elevation difference between the water inlet and outlet on your tubes. to really pull some water through those you need to have a J shape. whatdya think?

and as you pull water over the edge you might also be starving for more water in the box inside the aquarium.

 

[Anonymous]

i should clarify somehting... the J shape is not imperitive but it is cut in that manner for a reason.

the major factor here in your tank is elevation difference between the box in the tank and the box on the back of the tank.

 

[the Wizard]

Yes...DIY....I like this sort of thing....and as you guys know working in acrlyic is kind of fun. And none of the systems I've seen could span the 4" across the top that I needed...so I copied (I thought!). And if I built them wrong I'll build them again.

OK...yes....a J shape and a big height difference should pull much more water and that sounds like a solution, but the spill wall still needs to be at the height of the level of the water in the tank right?

Now wait a minute.....this is really confusing me. I'm gonna think on it over lunch hour. But maybe this is the problem, but I'm confused about flow rates and even which way the water should flow. I mean the pressure is greater at the entrance to the tube that is longer, right.

thinking.....

 

[Anonymous]

Yes...DIY....I like this sort of thing....and as you guys know working in acrlyic is kind of fun. And none of the systems I've seen could span the 4" across the top that I needed...so I copied (I thought!). And if I built them wrong I'll build them again.

OK...yes....a J shape and a big height difference should pull much more water and that sounds like a solution, but the spill wall still needs to be at the height of the level of the water in the tank right?

Now wait a minute.....this is really confusing me. I'm gonna think on it over lunch hour. But maybe this is the problem, but I'm confused about flow rates and even which way the water should flow. I mean the pressure is greater at the entrance to the tube that is longer, right.

thinking.....

you will get greater suction at the entrance of the tube that has a greater distance to travel downward.

yes, the spill wall needs to be at the elevation you wish to keep your water level. if that is too high for the water to spill over when the pump is running then you are low on water. if it spills over and fills the inner box of the overflow you are not siphoning as much water as you need to, whether that be caused by an inadequate J tube or inadequate drain piping off of that overflow box.
you have led me to believe that the box on the outside of the tank is remaining somewhat empty thus eliminating the drain piping as problematic.

if the box inside the tank is full in this scenario i would think you need either more downspout on the J tube or a larger J tube. if it is slow moving through the tube i would say you need the former.

now, if the interior box is emptying as fast as it is cascading over the spill wall and the pump is plenty wet and free of cavitation then you are running at capacity.

 

[the Wizard]

OK...where to start? You are right that there is very little water in the "spill well" of the overflow box. As soon as it gets there it goes down the retrun line. I just need more water in the "fill well" of the overflow. Sorry, I hope these terms are clear, I suspect they're not the ones you guys normally use. The "feed well" inside the main tank is always full, I drilled many little holes in the bottom, and I assume it's only function is to keep fish from entering the siphon tube.

To get more flow rate through the siphons it sounds like you're saying to make the "spill well" much deeper (currently 5" both inside the tank and outside the tank, with like a 4" tall spill wall, giving me 1" of depth down to the water level approx.) and then to make the J tube much longer on the "fill well" side. Now I could be wrong here, but I don't think that makes any difference at all....because deeper or not the water levels are still the same as defined by the height of the "spill wall".

Another example: Two garbage cans, both filled to the same level 3" down from the top. It sounds like you are saying to put a J tube siphon between them and water will flow, because one tube length is longer than the other. I don't think so. Agree...disagree? Can't add potential energy to the water with just a siphon. Or did I just misunderstand your thought?

If that worked I could rebuild the boxes to be deeper, but....

 

[Anonymous]

we have a language barrier here.

instead of clearling what i said earlier i will forget this "spill wall/well talk and only use 'interior' meaning inside the tank and 'exterior' being outside it.

on the interior box you should not drill holes in the bottom. it is best for the water to cascade over the top clearing any surface film. doing it this way also maintains the surface at a determined elevation which is preferable for asthetics and helpful when trying to determine sump levels, etc.

now, the J tube references made by me were not an implication that your boxes were not deep enough. i was saying that if your surface level inside the aquarium was not at a great enough elevation higher then the output of the J tube (or exterior box water surface level) then you would have less flow than you would if that tube (or interior water surface level) was longer. this is created by the increased gravitational pull that the additional water would provide travelling through the tube.

think of pumping a column of water up to a given height. if this system had a pipe running all the way back down to the original elevation there would be no need to factor in head pressure given this system is closed to the atmosphere. what is pumped up will fall back down and drag the water behind it. but if you cut that pipe halfway down you would additoinal pump horsepower provisions for half of the elevation change.
now if you lengthen it by 50% you are actually taking workload off the pump.

any clearer?

 

[the Wizard]

Wow...I am still a bit confused. I understand how the water moves, and by what forces, by it sounds like you are thinking of a system that works differently than mine. And I accept that yours is probably right, and better, because mine isn't working very well. But it does make this converstaion confusing. Maybe I should just call, unless you think many others are getting value from this.

If the box on the interior of the tank skims the surface as you said, which sounds good, it seems to me that when the pump stops and the water stops cascading into this box then the siphon will cease? Is there a drawing anywhere of the system you are describing?

 

[Anonymous]

Wow...I am still a bit confused. I understand how the water moves, and by what forces, by it sounds like you are thinking of a system that works differently than mine. And I accept that yours is probably right, and better, because mine isn't working very well. But it does make this converstaion confusing. Maybe I should just call, unless you think many others are getting value from this.

If the box on the interior of the tank skims the surface as you said, which sounds good, it seems to me that when the pump stops and the water stops cascading into this box then the siphon will cease? Is there a drawing anywhere of the system you are describing?

in a properly built overflow the water in each box will rest at a point that prohibits the siphon from breaking but as i am trying to convey, when the system is up the exterior box is deep enough to allow a lengthened j tube that will increase suction on the inlet end thus increasing flow as the interior box's surface level rises.

i edited this because i put an exterior where i meant to put interior.

 

[the Wizard]

Drawing anywhere? I understand the lengthened J tube part, but I still don't see how you maintain the siphon with no water flowing into the interior box? Seems like with no supply the siphon will do its thing and then go dry? Unless that level is controlled by the exterior spill wall...hmmmm....I need to see a drawing. Is there a website that shows this?