To skim or not to skim ?

I wish I had the link to the article I read written by an engineer about aquariums and floor support. It was very long and detailed but basically to sum it up, unless you have a really large tank thank you do not need to worry about the floor. I always said 75gal and under no need to worry anything over 100 better be careful about where you put it. I also took care of a structural engineer awhile ago and picked his brain about the subject. He said that without any visual inspection and not knowing anything about the house,joist, loadbearing walls, etc he uses 300lbs per sq/ft as the minimum your floor can support. Basically if you have a 55 gallon tank that is probably roughtly 550 lbs you are on 4 sq/ft which should support a minimum of 1200 lbs. Uses a stand with a wood runner on the bottom is much better at supporting and spreading the weight that a metal stand with 4 or 6 small points on the floor.

The article listed a bunch of myths and truths which included newer houses being better than older. That was basically false because older houses use a true 2X8 floor board instead of a 1.5 by 7inch board. Also older houses used harder slow growing woods for the beams and newer houses use quick growing pine and what not. It mentioned that the bare minimum for code is 40lbs per sq/ft for the WHOLE room floor. It sounds like nothing and you freak out and say, will I weight 200 and stand on ONE sq foot how is that?? Well the entire room is not all tank!! So to figure out what you can support at a bare minimum you have to take the width of the stand and multiply it by the length of the room and than by 40. So if you have a 4 foot wide tank sitting on the floor boards of a 12 foot room you can support 1920 lbs!! This is the total for the entire 12X4 foot section of the room though so if you put a tank on one side of the room, another on the other side of the room, and a cough in the middle between them plus you than you need to account for all that weight in the 1920lbs. You also have to remember that a piece of wood is stronger towards the wall than in the middle where time will allow it to bend and become weaker. It is best to put it agaisnt a load bearing wall spanning as many floor joists as you can. If you cant see it from your basement all is not lost. Your floor joist will run perpendicular to your load bearing walls and will start under the wall and be spaced 16inches on center.

These are the things you can do to help ease you mind when placing larger tanks. Once again though the difference between the first second and third floor is all the same. THe floors all are build to the minimum or greater code! I just placed a 65 gallon agaisnt a non load bearing wall knowing that the floor joist are right behind it, directly under it, and about 2 inches in front of it to support the weight. The room is 16feet long and has oak hardwood flooring.

Sorry for the long winded reply I will search for the link to the article would made a good sticky!!

 

Just realized this discussion has good away from the OP question about skimmers and instead went to tlaking them into a larger tank. As for a skimmer, your 55gallon skimmer may be too large for a 20gal tank. Not exactly overskimming but if the size of the skimmer is too large than you need enough organics to build up the head of foam to allow it to remove organics. If you place a large 200gal capable skimmer on a 125gal tank you hae 125gal of water to skim and pull organics which leads a suffiecent head and good skimmate keeping organics in the reef low. If you know place that same skimmer on a 40gal tank than you only have 40gal of water to pull organics off of. To build a head that allows the skimmer to work you need to have a much larger organic load in the reefs water basically making the skimmer very ineffective by only skimming higher levels or organic material.

Basically your skimmer is too large for a 20gal and you need a smaller skimmer with a smaller tube and collection cup!! But no, skimming is not required by any means and you can over skim and starve corals. IT does give you some wiggle room for error in case you miss water changes, overfeed, lose livestock, or neglect your tank for a period of time.

 

Found the link

http://www.african-cichlid.com/Structure.htm

 

With a 20H I would run a hob fuge/skimmer combo if I was wanting SPS that is, and funds allowed. + the added water can help ALOT. Plus with the right system you can use it on the 55 gallon if you ever get it set up.

 

This is a good way about thinking of the skimmer. I know in the past I've wondered about this topic.

good explanation!

 

Thanks for all the replies !! As for my 55, I had it running for 9 months in my apartment. When doing the pest control service on the apartment below mine I noticed about a 3 to 4 foot long crack in the ceiling right where my tank was setting. And a small bow or dip also in the ceiling like something heavy was causing the floor to sag. That something heavy was my tank at about 700 lbs. To be on the safe side I drained it and downsized.

 

Here's a quick shot of the 20. Nothing special but I like it.

 

Skimmers are not very efficient on small tanks, there just isn't enough water volume/organics to keep a constant foam head. To make it really work well requires a lot of adjusting, or it probably won't do all that much, except maybe overflow a lot if adjusted too aggressively. I wouldn't bother under 30g personally. GAC seems to be more effective than skimming, so, should be plenty sufficient on a small tank; it just gets expensive on a large tank, so, skimmers start to become more cost-effective.

 

So, assuming the skimmer is working correctly, if there is not much foam/ intermittent foam being produced, then you are probably over skimming? Just wondering because I can go two weeks and only have a quarter inch of skimmate in the collection cup. Also, the foam head is intermittent at best in my tank. I feed modestly every day both corals and fish.

 

There is always foam at the top of the neck but it may take a week to fill up the cup. After a water change the cup will fill over night though.