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Aquarium.Net Jan 97 Q & A

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Questions and Answers

By Bruce Davidson


Do freshwater tanks need to be grounded too? Is your magazine (Aquarium.Net) geared for saltwater tank owners only?

Michelle M. Cooley Gilbert, Arizona.


While my article was written about marine aquariums it certainly applies to freshwater aquaria. The lateral line system is something most if not all fish have in common. As I stated in my earlier article the lateral line is used to sense electrical impulses and fields, among other things.

Remember that not only should you ground the aquarium water but you should also test for stray voltage. If your aquarium has any voltage in the water you should try to isolate the source and eliminate it.

Currently the majority of the articles that appear here on are dedicated to marine topics. Take a look at this months issue and you will find a new monthly column by Mark Leher. Mark will be providing us with freshwater insight every month. We hope to have a few more freshwater names in the future.

ttys Bruce Davidson Louisville KY Philoicthyoecetes


I was wondering if you could explain briefly how a skimmer operates or direct me to an article here that would shed some light on the subject. I know it is supposed to remove wastes from the water, however, I'm curious as to the actual method used to do so.

Thanks for the help! Louis Wagner


Protein foam skimming or foam fractionation is one of the best tools we have for managing marine aquariums. Organic molecules have one end that loves water (hydrophilic)and one end that hates water (hydrophobic). In other words organic waste likes the air water interface. A bubble is the ideal place to collect these organics. The organics will form a "skin" around a bubble. The skin keeps the bubbles from popping and forms a foam that is pretty stable. The protein skimmer is a controlled environment that collects the organic rich bubbles/foam and removes them from the system. The smaller the bubbles the more surface area you have. The more surface area you have the more organics you can collect.

If you use an efficient foam skimmer on your aquarium you will rely less on biological filtration because the majority of the waste will be removed from the system. This means that you will not build up nitrate as quickly.  Once the bacteria in your filter grab hold of the organics they are processed into ammonia then nitrite and finally nitrate, the foam skimmer cannot remove these substances. As a matter of fact the biological filter should only receive water that has passed through the foam skimmer first. This will give your foam skimmer first crack at the organics. This is not an absolute must but it is the best configuration.

According to Martin Moe some of the things found in the foam a skimmer produces are water soluble proteins, amino acids, organic dyes, fatty acids, fats, carbohydrates, enzymes, detergents, inorganic compounds, metal ions like copper and zinc, iodine, phosphorus, algae cells, protozoa, bacteria, and particles of buoyant organic detritus.

ttys Bruce Davidson Philoicthyoecetes


Well I have just lived through a catastrophe that I hope never to repeat. I believe that in adding live rock (LR)I introduced ich and also stretched my filtration to it's limits by simultaneously adding fish (which I) lost. Currently I have a 55+ Oceanic with under gravel (UG) , 550 powerheads and an Emperor 280. The tank has adjusted it's population. I removed the LR and started a mini-reef with no fish an unfortunately d am down to a clown and damsel in the 55. The irony is the substrate was filthy but water chemistry never suffered. I have tentatively decided to replace the UG with a wet/dry (W/D) system that will turn over the tank about 10X / hr with a skimmer and fluidized filter and use live rock with a coral sand substrate. First, what do you think of this and how do I prevent a return of the dreaded ich monster to my tank ?

Bruce I really appreciate all your help, thanks again and I hope you and yours have a Merry Christmas !

Kevin Biegler Mound, MN (near the Twin Cities)


While live rock can carry parasites into your tank it is not the most likely cause. Most likely the rock was not fully cured and the slight rise in ammonia and the fact that you just remodeled the tank was enough to suppress your fishes immune system. In the stressful state the parasites that your fish normally carry seized the opportunity to feed and reproduce. Even more likely is that the newly introduced fish were carrying parasites. I did not see you mention a quarantine (Q) tank. Of course there is the possibility that your clown fish and damsel picked on the new fish. Both of these fish can be quite aggressive. I think it would have been best to put the new fish through a Q period of at least 20 days in another tank. Once the fish have been introduced into the main tank you can use the Q tank for the rock. When the rocks water shows no ammonia and nitrite it can be safely put into the main tank. Keeping the rock in a tank without fish will kill most of the parasites in 25-30 days.

The fact that your substrate was filthy comes as no surprise. UG filters are very efficient at catching particulate matter. In my opinion this is one of the biggest drawbacks of the UG system, after a wile the detritus may start to clog the crushed coral substrate and slow biological filtration.

The first rule of filtration is never use a biological filter as a particulate filter.

The second rule is: Manual removal of waste is better than anything else. If we only had some type of filter that would catch organic waste and particulate matter. If that magic filter would physically remove it from the system so that it could not be biologically broken down and put back into the water this aquarium stuff would be easy. Well we have that magic filter and it is called a protein foam skimmer. The majority of the waste generated in a marine aquarium can be removed by foam skimmers. If water passes through biological filtration or particulate filtration before the foam skimmer you have robbed it of the opportunity to do it's job.

This brings us to filter selection. The first thing I wanna say is: bio balls, fluidized sand, wet dry, DLS and any other mystery media is just a biological filter. Biological filters process organic waste into nitrate.  You do water changes to reduce the nitrate in the system. If you are going to use a biological filter is should ONLY receive water from the protein foam skimmer. In my opinion all of the biological filters work the same and give you the same end result. Chose one that can easily be used after the foam skimmer. The same holds true for particulate filtration.

My preference for filtration for both a fish only and a reef tank is about one third of the aquarium full of live rock, 2-3 inches of fine calcium sand on the bare bottom, full spectrum lighting and a big ole foam skimmer. I do not use biological or particulate filtration in my tanks.

I think your projected water turnover rate of 10 times the tank volume and hour is a bit high. Most of the overflow devices out there can only handle 300-400 gallons per hour (GPH). I think that is fine for your size tank. If the pump is going to power the foam skimmer and return water to the tank I suggest one that will deliver 600 GPH at 4 foot of head pressure.

The best way to prevent ich is keep your fish in good health and put every new addition through a Q period. Good health means a regulated photoperiod, the proper diet and plenty of it, lots of hiding places in a natural setting and non aggressive tankmates. Of course on top of all of this you will need perfect water quality with stable salinity and temperature.

Thanks for the holiday wishes Kevin, I hope you had a good one.

TTYS Bruce Davidson Philoicthyoecetes

Created by liquid
Last modified 2006-11-18 15:17