Surface Skimming and other issues - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 4 Old 07-23-2008, 07:55 AM Thread Starter
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Surface Skimming and other issues

hello everyone,

I've got a 130 gallon tank with about 175lbs of live rock in it. The tank is just about 3 weeks - 1 month old and is the type of tank is an MJ Baolai. The system comes complete with cabinet, sumps and tank of course. The tank comes with 2 plastic rectangular bucket type sumps. Each is about 15 gallons and is joined by pvc plumbing. The water coming from the tank enters the first sump, which then overflows into the second sump.

I want to introduce some mechanical filtration via foam/floss and charcoal. The first sump can be sectioned off so that floss etc can be inserted. Withinn the same first sump, after the mechanical filtration there will be a protein skimmer which flows into the second sump. So the second sump is fed via the protein skimmer and the overflow from the mechanically filtered water. The clean water is then pumped back up to the tank via a submersible pump in the second sump. I also have 2 wavemaker blowers inside the tank, one on each short side of the tank. This creates a nice current inside the tank and some surface activity as well. Hope I'm clear enough.

The water is returned to the tank via a hose with a 90 degree fitting at the end which creates bubbles in 1 corner of the tank. Should I have aeration in other areas of the tank as well via airstone etc?

My readings are as follows:
ph 8.4
salinity 1.019
ammonia 0
nitrate 0

I know my salinity is a bit low and this will be remedied today.

I've got 4 fish in my tank and they are a triggerfish (who's going back to the shop today), two wrasses and a clownfish.
The only filtration I've got currently is my live rock. As mentioned above, I'm going to add floss and charcoal later on today.

There's a bit of surface scum developing and I need to know a bit more about surface skimming. The water has a very slight haze or cloudiness to it. IIs this the surface scum mixing back into the water? How can I get rid of this? Is there a complete system I can purchase?

Thank you all for reading.
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post #2 of 4 Old 07-23-2008, 03:37 PM
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Re: Surface Skimming and other issues

OK, First, How does the water exit the display to reach the sumps?
Some folks try to use fabricated methods that are essentially ineffective at performing the necessary task of surface skimming. If the tank is not equipped with the "reef ready" features of an internal overflow and required plumbing, then the use of a pre-filter (external overflow) would be required. This takes the water from the surface and sends it to the sumps.

If you currently have a properly designed overflow system in place, then the next step it to look at your surface agitation and flow within the tank. Sometimes improperly directed flow can cause a current at the surface of the water that traps the proteins in certain areas of the tank.

It appears that you are working towards a fish-only system. While I'm not entirely sure as to any benefits of bubbles in a fish-only system, I can saythat bubbles in a reef system are unwanted for several reasons. Some of those reasons would lead me to believe they are unwanted in a fish only system as well. These bubbles in the display will also add to the collection of proteins at the surface as the bubbles in the display are working much like a protein skimmer does. Personally, I would seek to eliminate the bubbles you have already entering the display from your return line. You should have plenty of aeration in the water from the trip down to the sump. Another member, Pasfur, has a good deal of experience with fish-only systems, perhaps his input here might help provide some clarification on any benefits from bubbles in a fish-only system

Additional mechanical filtration in a system with live rock and protein skimmer is a topic of much debate. Most aquarists agree that it is a poor choice. Detritus and proteins collect within the filter materials and essentially feed the production of nitrates in the system. In addition to the Protein Skimming and Live Rock I use only a Filter Sock, changed every 3 days, for water polishing.

There are several all-in-one sump systems available to the hobbyist, but it would be far less expensive to go out and buy the Pre-filter and Protein Skimmer, then design your own system.

If you're looking for more information on sump systems, I invite you to check out the article "understanding sumps" stickied in the 'sumps and refugiums', and 'member submitted articles' sections of Fishforum.

Hope that helps

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post #3 of 4 Old 07-25-2008, 05:40 PM
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On the point of mechanical filtration... i agree completely. Mechanical filtration in a marine system can unintentionally cause all sorts of problems unless the filter pads are cleaned DAILY. Given that most hobbyists are not up to a daily cleaning, it is best to not use mechanical filtration at all. If anyone wants to start a new thread on the topic, i'd be happy to elaborate, although it can be a lengthly debate. For now, lets just say that mechanical filtration can cause phosphate buildups and to some extent Nitrate accumulation.

On the bubble topic, I would never intentionally introduce bubbles into a marine display. A properly setup marine aquarium will have considerable water flow, which if properly directed would eliminate the need for an air stone. If you have dead spots, then you need to add an additional power head, potentially angled at the surface to agitate the water. The biggest negative to bubbles is excessive salt creep, which can be overwhelming.

My particular system does not have a surface skimmer, so i also fight the problem of surface scum. My simple solution is to manually remove the surface scum when doing my weekly partial water change. I change 10% water weekly, and angle my siphon hose to create a strong vacuum of water directly off the surface. This easily removes the scum which only builds up slightly in any given week. I am a believer in partial water changes, even in marine systems which utilize heavy skimming. I am a bit old fashioned that way and recognize the argument against the need for partial water changes. All I can say is that I have better success when i do partials, which is after all the ultimate test.

One more quick comment. You said that live rock is your only filter. Actually, your "filter" is live rock and the protein skimmer, which is exactly what you want in a marine system. This is not a bad thing.
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post #4 of 4 Old 07-26-2008, 11:56 PM Thread Starter
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guys thanks for your opinions. I will read them carefully and respond.
lutch is offline  

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