Too much skimmer?

Powerman,
I'm confused how an oversized skimmer doesn't pull out as much as a "properly" sized skimmer? I know what you are saying, and by no means doubting your knowledge. I'll be the first to admit by reading your posts over time that you are MUCH more knowledgable than me when it comes to anything in this hobby.

In my case I put a BM NAC6 on my 20DT w/ 20sump/fuge. Way oversized skimmer than I bought for a 75 I'm building but wanted to see how it performed while my bigger build is on hold. I noticed how you said an oversized skimmer that has too large of a neck will not allow the foam to form to build up and pour over into the collection cup. I've noticed that while there may not be a steady flow of skimmate pouring into my collection cup, the skimmer still traps that skimmate and builds up in the neck until there is enough to pour over into the collection cup. So really, even though it hasn't been collected and removed, it's still trapped in the skimmer neck. So tecnically isn't the skimmate still removed from the water column and out of circulation with the rest of the tank water?

I think a properly sized skimmer may pull out a more consistent but smaller amount of skimmate, where as an oversized skimmer may pull out a much larger amount of skimmate, just not as frequently.

 

As long as the skimmer isn't too small, it's cool. A too-large skimmer will pull out approximately the same amount as a similarly-engineered skimmer of a smaller size. The issue is whether the skimmate ends up in the cup or on the neck at that point, which can make maintenance a pain.

 

You were not seeing things. You're right on track. Another thing I found interesting is that sure we know all about softies and LPS and SPS.... yet even in each of those catagories there is a wide variety of requirements and what will be best for them. Not everything populates the same zones on the reef and some softies and LPS can live in very dirty waters. Like near a river or lagoon with very high nutrient levels.

I had a lot of zoas and in time with my system they all withered away. I moved to more low nutrient system and SPS and the shrooms and zoas did not appreciate it at all.

So with a fuge and proper flow and a good skimmer and maybe some GFO for a SPS tank you can get nutrient levels below what some other corals are happy with, but that does not mean that the action of skimming can totally strip water of all nutrients. Dissolved organics are water loving and water hating, skimming only removes water hating and one recent study showed for it to not remove 100% of those.... that still leaves all the rest of the others.



***One important consideration with good skimmers is that they do such a good job that we can feed more. That is not a drawback... that is an advantage. Skimmers generally remove some dissolved organics but also remove a good amount of solids like a mechanical filter just by the action of being caught up in the foam. As a result we can feed more of the good stuff and still maintain clean water by not allowing excess and waste to accumulate. The result is cleaner water and healthy faster growing coral. Many times people report that thier skimmer is too much when in fact they are not feeding enough.

On a reef food is available 24/7 in very small amounts. There is no "feed" time and there is no way we can simulate that in our tanks no matter how small we dose automatically and many times a day. So we can use all the weapons at our disposal to totally strip our water of nutrients.... but the end result isn't to have totally pure water.... the end result of marco algae, GFO, biopellets, carbon dosing, good skimming, and WC is to have very clean water and STILL be able to FEED A BUTT LOAD of food so that our corals can still be healthy, grow and multiply in a glass box far from it's natural environment.

 

You're not off base either. there was an article written by Homes-Farley suggesting that dry skimming removes less organics than wet skimming. His reasoning was that giving the dry foam more time to drain you would naturally loose some organics back to the water. Seemed reasonable to me....

Then I thought about what you said about if the organics are bound up in the skimmer but just not collected up to the cup then effectively they are removed from the system. So I asked him about it and he said that he never had any data or meant to suggest that that was a sure thing..... just that in his mind that should be what happens.... but in reality there really ins not evidence to show that wet or dry removes any more organics than the other. They are equal, just the dry skimmate has less water in it diluting the skimmate.

So while organics maybe bound up in the grossly oversized skimmer body and just not made it to the cup yet, they are effectively removed from the system. The grossly oversized skimmer though will be very difficult to adjust and it will have to be run a lot wetter with a much higher water level just to collect some of those organics to the cup. The reasoning is that organics will build have to build up to a higher level in the system for the grossly oversized skimmer to produce therefore not achieving as low of a nutrient level as a properly sized skimmer could.

In reality, perhaps that is not the case and that both can achieve the same levels. However, what is a fact is that a huge skimmer on a small system will not remove "more"... and that skimmer will cost more, take up more room, use more power, and will have to be run in a less optimal manner just to get some skimmate all for zero advantage over a quality properly sized skimmer. Now if you are just changing tanks and throw on something in the mean time or are just playing around, no big deal. Yet when looking at buying and specing a skimmer for a given system.... it is quite silly to think a gigantic skimmer is going to be a good buy.