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View Full Version : How to make water level constant in the sump, skimmer and return pumps are different


dendro982
11/15/2007, 05:57 PM
Hi, need advice on adjusting flow in the sump.

90g undrilled tank with overflow box, tubing from there goes to the micron sock in 15g sump with no baffles, just plain glass tank. Next is ASM G-3 skimmer, 550gph pump. Gate valve reroutes the clean water to the return pump Ocean Runner PH 2500, 650 gph (if zero head loss). Pump is connected to the PVC spray bar along the bottom, with antisiphon hole at the top, of course. It's all.

Water intake level of the outflow box is adjusted, so when return pump and skimmer are off (imitation of the power failure), the sump will be filled to the brims, but will not overflow. Little more, than half of the sump, when all is working.

Now:
1. I used filter floss roll as prefilter in outflow box. It starts to influence water level after several hours, not even a couple of days.

Water level slightly drops, skimmer stops producing skimmate.

2. Tried to place skimmer in rubbermaid container, to imitate baffle, so if there will be constant water level, and overflowing water will go just over the container edges, in the sump. Flow from the tank goes there too.

Didn't worked: skimmer removes ~550 gph right to the return pump, by gate valve mod, return pump removes less, because of the 3 ft head loss and resistance in the spray bar.

Had to remove container from the sump, difference in inflow/outflow made this system unstable.

What can be done?

I had read a lot, before doing that, but clearly missed something.
Thanks.

Ah, micron sock is changed daily.

ufans
11/15/2007, 06:27 PM
1) Can you increase the size of the sump? The size of my sump is the same size of the display.

2) Put a check valve on the return line after the return pump so that when the power turns off NO water is pulled back into the sump. Ref; http://www.marinedepot.com/ps_ViewItem~idProduct~FT9044.html

3) Add baffles... The return pump will always vary. Baffles will ensure that the volume of water that the skimmer sees is constant.

Misled
11/15/2007, 06:30 PM
You said in your post the filter floss affects the water level after several hours, so I think that's where your problem is. Remove it and see what happens without it for the same amount of time. If that's it, put a regular overflo box sponge on it. These should not plug up as fast. You're also loosing some water to evaporation, so that's probably not helping either.

DrBegalke
11/15/2007, 07:23 PM
you need to either dial back the return pump, increase the capacity of the overflow, or remove the prefilter media, or some combination of all of the above.

DrBegalke
11/15/2007, 07:26 PM
Also, be sure to test the system to see what happens in a power outtage, or in th event that the overflow gets completely blocked.

Neither the sump or the main tank should overflow...

dendro982
11/16/2007, 07:16 AM
Thank you, trying all of the advised in different combinations.
Will take a look at check valves in LFS.

What else should I know or try?

jefnalyssa
11/16/2007, 07:44 AM
IMHO I would not use check valve it will end up failing. What is your overflow rated for?

plyr58
11/16/2007, 08:51 AM
use a break siphon hole in your return instead of a check valve.

USC-fan
11/16/2007, 10:23 AM
sell the asm and get a recirc skimmer.... a lot less headaches and water level doesn't effect the skimmer.

AZDesertRat
11/16/2007, 10:44 AM
Having the return spray bar on the bottom is a very scary situation. You are asking for a disaster and it will be ugly.
Drilled siphon break holes are a makeshift solution that is only sometimes successful and will eventually fail. Thye require constant cleaning and maintenance and even then what is stopping a snail from parking over the hole(s)? It could also be algae which is common or a bit of frozen or flake food.
Check valves have no business in an aquarium environment. Just like drilled holes they can andwil fail. All it takes is one single grain of sand to defeat a flapper and you are doomed. No matter how well or how often yoy clean the valve there is no guarantee a small snail will not get caught on theseating surface and its all over.

The best solution is to move the spray bar close to the surface so you can easily calculate the amout of water that will siphon back to the sump in a power outage. No check valves or driled holes are needed as is no maintenance. It provides you the best level of protection, an air gap, once the water siphons down to the spraybar level it is impossible for it to go any further.

In my case I have a 100G display with a 30 G sump. When my power goes off I siphon less than 4 gallons back to the sump so I always maintain at least that much room in my sump. I have baffles in the sump so the skimmer level does not change drastically and even without a topoff system I can go 4 days before adding 5 to 6 gallons of topoff water.

kevin gu3
11/16/2007, 11:31 AM
Wait, does your skimmer return to the sump or directly to the return pump? If the latter then you have a race condition no matter what - unstable.

Divide the sump in two parts with a permeable baffle (say a bucket with holes sitting in the sump). Baffle should just prevent uneeded mixing of the two parts but still allow levels to even out by gravity.

Dump tank into "dirty" part and have skimmer pump pull from it. Have skimmer output go to "clean" part. Put the return pump's inlet in the clean half. That should eliminate the race problem, you won't have to try to equalize the flow of two pumps.

dendro982
11/17/2007, 08:08 AM
What is your overflow rated for?
600 gph, but it's made with possibility to add another 600 gph box.

use a break siphon hole in your return instead of a check valve.
Done.

sell the asm and get a recirc skimmer.... a lot less headaches and water level doesn't effect the skimmer.
Which one is at the low price end, but still doing a job?

The best solution is to move the spray bar close to the surface so you can easily calculate the amout of water that will siphon back to the sump in a power outage.
My spaybar was made for moving debris from the bottom back to the bottom front, for easier removing.
BTW, the first holes give more flow, shrimps left the windy place and moved in opposite end of the tank... Real headache.

Wait, does your skimmer return to the sump or directly to the return pump?
If the latter then you have a race condition no matter what - unstable.
In Calfo's thread about making any protein skimmer work efficiently, http://reefcentral.com/forums/showthread.php?s=&threadid=554786&perpage=25&pagenumber=1, one of the way was to add water well for a skimmer (baffle or rubbermaid container, higher, than water level in the sump), so water from overflow box goes to the skimmer, and the gate valve mod moves skimmed water outside the skimmer's section (whatever baffled or a separate container), right to the return pump.

If inflow in the slimmer section is higher, than removing, water overflows skimmer container edges and goes to the main part of the sump.

If lower - well, it, my case, the water level in the skimmer section drops, and the whole thing is not usable... :(

Overflow boxes using supposed to be very simple and straight-forward.

I did my best - used 650 gph return pump, and 550 gph skimmer pump, but after head loss and loss of flow in the piping, the return pump flow become lesser, than skimmer's. Buying next, and next return pump to match the skimmer's outflow is not a preferred option, as you know. Any other way do make the whole thing work?

Divide the sump in two parts with a permeable baffle (say a bucket with holes sitting in the sump). Baffle should just prevent mixing of the two parts but still allow levels to even out by gravity.
Holes at the top, at water level only, or the whole bucket/contained should be mesh-like?

Thank you all for the help, still post any possible suggestions.