SeaClear System II Help! - The Planted Tank Forum
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post #1 of 4 (permalink) Old 12-19-2014, 02:04 AM Thread Starter
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SeaClear System II Help!

Hey, I recently picked up a 75 Gallon SeaClear System II from craigslist for cheap, and was wondering a few things about setting up as a planted tank.

1) With the built in wet/dry filter in back, there are a series of passive outflow holes along the bottom of the dividing wall that are only a couple inches off the base of the tank. I wanted to build the substrate layer higher than that and was wondering if there is some way that I can build in front of these holes without compromising the filtration? Maybe with a row of rocks along the bottom that sit in front of the holes or something like a sponge. I could try to layer the substrate above these holes and hope that the flow doesn't disturb it too much, but I'm not sure how this will affect the filtration... and I'm almost positive there would be permanent holes in the substrate from the flow if i didn't break it up somehow.

2) Where is the best place to add pressurized CO2? I read on another post that adding it to the sump would cause an excess amount of loss before it reaches the main tank, but would it really be that severe? I don't have a problem with adding it to the main compartment, one airline hose is not that noticeable, but would the concentration loss still be bad?

3) Is is possible to expand the top cutouts of the tank to make it easier to add the hardscape materials, maybe by an inch or 2? I wanted to use driftwood in this tank but getting it in those 17"x7" holes is going to be a pain in the rear.

Any advice is appreciated! I am going to use this tank no matter what but would ideally like to do what I want with the scape... my biggest concern is the passive outflow holes from the sump to main tank, worried that it will blow the substrate all around that back wall. Here is a link to the tank:
The outlets from the sump pump to the main tank are vertical along the rear right wall panel, and the passive outflow holes run along two thirds the bottom of the tank from the right.

In hindsight I probably should have just purchased a glass tank, but I liked the idea of having the filtration completely hidden and built in... Oh well! Thanks for your help!

Last edited by MoldyMayo; 12-19-2014 at 03:05 AM. Reason: error
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post #2 of 4 (permalink) Old 12-19-2014, 05:12 AM Thread Starter
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If you can answer any of these questions for me I'd appreciate it!
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post #3 of 4 (permalink) Old 12-19-2014, 03:53 PM
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Oops, I started then got distracted.

I had a 3' seaclear way back when. Loved the built in sump. Frustrated with the lack of depth. No CO2, didn't know about NPK+micros, loaded 6 full length T12s over it but everything was super green and grew like mad. Okay 10% of the green was algae and unless I scrubbed the tank weekly you couldn't see inside but the plants thrived.

I'd try out blocking the holes to see what happens. Fill the tank with water and start up the pump. Block the holes with something and compare how the system is running. If the sump area starts backing up then you could drill out the upper holes to improve flow but I bet it will be fine. I seriously doubt substrate will be blown away from the area if you are using something with some weight to it and not at all if it is passive movement. If it does want to blow then putting a piece of tile or slate with a couple of rocks against the area should take care of it.

I'd start out with the old CO2 line stuck in the pump intake cage trick at first. Works pretty well. Then you could try using a very good quality airstone as diffuser placed just below the pump intake if you didn't care for the bubbles. Or get a better quality diffuser and place in the same area so bubbles are drawn into the pump right away rather than floating up. Or replace the impeller of the pump with a needle type to make tiny bubbles or just mutilate one by clipping or drilling holes in the fins. I even made a reactor with a small plastic bottle with the cap drilled in three spots with water coming from a venturi set in the pump's return, line going to CO2 tank and another draining water back into the pump's intake cage later, not on the SCII but it might fit. That one worked then it didn't work, no idea how I messed it up. Since SCII are quite tightly sealed I doubt the CO2 is going to go anywhere anyway but you could also cover the water surface in the pump area with a bit of bubble wrap as well.

The CO2 loss from sumps is quite the myth. It started out with yeast CO2, with pressurized gas you don't need to be quite so conservative. I have used regular sumps with CO2 on my planted tanks for 14 years now [+? years with no CO2 on the SCII] and wouldn't have it any other way. I'd much rather have to put in a bit of extra gas than have fish suffering from low oxygen because I am afraid to waste CO2.

I wouldn't mess with bracing ever on any acrylic tank! I am quite sure this company has designed these things carefully to use the thinnest possible material and then idiot proofed it with those tiny cut outs. You could make up your hardscape, cut it narrow enough to get into the tank and screw it together then unscrew, place in tank and screw back together again. Did that once. Super not fun but it worked. And it may not even be necessary, you can get amazingly large things through. My 180 long's 3 openings were the same width but longer than your tank's and I got a 24x24x12" frankenstump in there without having to take anything off. See that tank's journal to see how big it was.

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post #4 of 4 (permalink) Old 12-20-2014, 05:57 AM Thread Starter
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Thank you so much for the reply Kathyy, I am going to try to plug the holes tomorrow while it is cycling and see how that affects the system. I just wanted to see if anyone had any input as to whether this would cause a severe problem in the sump system.
With CO2 I was thinking that I could put the diffuser right under the pump intake and that would be good enough, glad to know that it doesn't severely reduce the benefits or anything having it in the sump, I'm not even going to worry about that anymore.
And finally, I've been thinking I won't mess with the cutouts either, I can probably fit the pieces that I want in the tank still and don't want to risk cracks or worse, having 75 Gallons of water flood my condo would be pretty disastrous, and annoying as heck if I caused it!
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