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Old 01/06/2016, 11:20 AM   #53
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Originally Posted by biecacka View Post
Gotcha. Thanks! Can you explain to me what lowering the skimmer into deeper water will do or is it not really needed with the addition of more fish. It is amazing to know that 20 fish in my tank is a light load for this skimmer and that 30 is moderate. I don't know about the DOC's, I assume there are plenty. 20 fish for a year, feeding 2-4 vibes a day and producing no skim for a year. My nitrates are 75-100 as of last night. There has to be something in there I would think. But the skimmer is almost dialed in. I am going to thicken it up just a bit from the sludge it pulled the other day.
I dropped it to 26 and shut the wedge a bit. I'll wait an hour or so and tinker with it again. In used to the beckett where you let it set for hours/day between adjustments.

Lowering the skimmer deeper into the sump (same as raising the water level in the sump) will have the same effect as closing the wedge. It will raise the water level in the skimmer. If you need to close the wedge beyond the 50% point, then I would suggest raising the water level in the sump or lowering the skimmer so you aren't having the resort to restricting the flow out of the skimmer too much as that can cause surging in the skimmer. I think I mentioned it before but if not, I will mention in now, I always try to adjust the skimmer level via the sump so I start with the wedge pipe nearly wide open. I find the best setting for the skimmer in terms of bubble quality and then make subtle sump level adjustments to get the level in the ball park with the wedge wide open. Then all I do is make very subtle adjustments to the wedge pipe to raise of lower the level inside the skimmer. Keep in mind that the speed of the pump has a direct impact on the water level in the skimmer just as it does the bubble quality. I Adjust the pump to get the thickest foam I can. In the case of the old Red Dragons with the adjustable volute, that meant turning the volute. In the case of the RD3, that requires finding the sweet spot for the pump. As I said, every system is different. It takes a bit of playing around. You find a ball park setting with the pump, then you slow it down and see how the foam looks a few hours later. Then you speed it up a bit and see what that does. A bit of testing and you find the sweet spot. Once I find that sweet spot, I then adjust the sump level to get the water level where it transitions from bubbles to foam up to the base of the neck at the top of the part where the neck meets/threads to the body. Then I use the wedge pipe to adjust it up from there. That is how I find tune my skimmers.

As for your nitrate issue, I suspect that is the result of a couple things. First, skimmers remove dissolved solids. They don't really remove nutrients although these solids eventually will break down and contribute to nutrients. The big factor in nutrient reduction like nitrates is bacteria. In the case of the natural approach to bacterial reduction in our tanks, live rock plays a big role in that because it provides the surface space for the bacteria to congregate. This is one of the benefits of deep sand beds as they provide additional surface space for denitrifying bacteria much the same way live rock does. Some people use fake rock for their aquascapes but fake rock isn't as porous and doesn't offer the same surface space within the rock like real live rock does. Often the tanks that have high levels of nitrates don't have a lot of live rock or at least enough live rock for the load. The other factor is waste accumulation in the substrate. Having waste break down in the sand and not vacuuming with regularity is a recipe for high nitrates. This is where lots of flow can help so that waste is sent over the overflow so it can be skimmed out and or filtered out via socks. Refugiums and turf scrubbers help consume nutrients from the tank but they don't remove dissolved solids so you still end up with particles in the water and detritus that the skimmer would otherwise remove. Cabron dosing generates bacteria that consumes nitrate causing nutrients but it is a crutch or band aid in my opinion.

At the end of the day, the skimmer is part of a complex solution. The skimmer removes solids that become nutrients. The skimmer adds dissolved o2 to the system. The combination of those two factors increase ORP. The skimmer is also an important part of the gas exchange process that removes nitrogen from our water but it's not the end all be all when it comes to nitrate issues. Its only one part of the solution.

In my tank, I don't have detectable nitrates despite having a pretty good load. I attribute that to a lot of live rock. I have somewhere between 700 and 1000 pounds of it. I also run a 30"x36" deep sand bed in my refugium that has a combination of mud, sand a live rock rubble. I also run two refugiums. I have a high amount of flow that is well planned out to insure that stuff doesn't settle on the bottom and I use filter socks to catch the solids that pass into the sump. Lastly, my tank has been up for around 18 years and is very well established. I have a bacterial bed that can keep up with anything I throw at it.

As for 20 fish being a low load vs 30 being a moderate load.. Load is relative to waste from the fish and feeding. You can have 30 small fish in the tank and have that be a small load. Size of the fish and how you feed is where dissolved solids (DOC's) are generated. The amount of waste that skimmer produces consistently is the best sign of your load. This assuming that the skimmer is tuned well.

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