water wont stay clean

[srezack]

Afternoon guys,
So for the past 3 weeks we have been struggling to keep the water clean. There keeps forming a brown film (for lack of better word) across the top of the water, and the sand is turning brown shortly after we clean it. We have done 3 30% water changes over the past month and it still isn't working. I have changed the filters on the back of the tank.. we have a biocube 33 gallon. we have added nothing new to the tank or taken anything out. what can be causing this?

 

[mnavick]

How old is the tank?
What type of rock and how old?
How was the rock prepared before adding to tank?
Are you using RODI water?
What is the TDS?
What type of salt are you using and how is it being prepared?

 

[srezack]

Well the tank is now 4 years old. The last time we added anything was back in February and we use rodi water with new filters (only made 150 gallons with it so far with the new filters) and we are still using Kent reef salt like it always has been used. We are using 2 different foods but that was something we changed a little while ago... Emerald entrée which has we always been used... the other one is the same company but just shrimp and brine... now that I am typing this I am wondering if this might be the thing causing the change? but that should be safe. the rock is the same rock for over a year now plus the rock that's over 4 years old

 

[srezack]

I know we want to see if anyone can come and frag some zoas, pulsing xenia and feather dusters for us. we just wanna clear some of the rock for the other colonies that we want to grow to grow.

 

[wpeterson]

If you're getting a biofilm on the surface of the water, you should try running activated carbon in a media reactor or a media bag if you don't have a reactor. It sounds like you have a large amount of dissolved organic matter which accumulates at the surface of the water.

Whatever is growing over your sand is likely something different (cyanobacteria, hair algae, or dinos). This is usually due to excess nutrients building up in the tank. Sandbeds and rockwork can absorb nutrients, but at a certain point they are full and will leach nutrients back into your tank. What are your Nitrate and Phosphate levels? Controlling your nutrients will help you to prevent the growth of nuisance algae, but if you're still seeing signs of high nutrient loads it may be leaching from your rockwork and sand after years of buildup.

If this is the case, it's a tough position - because even if you increase your nutrient export dramatically to pull nutrients out of the water column, you may see nuisance algae and bacterial growth at the source of the nutrient leaching - on the rocks and the sand.

 

[srezack]

What is the activated Carbon? we don't have any of that. is that like the bioballs? we don't have those in this tank either. It is a bio-cube tank but we have just the blue filter and the big green screen thing that goes before the return pump. Is this something we will stick in the back under the filter or before the filter?

 

[wpeterson]

Carbon is produced in several different ways, but as a water filter it has a very fine pore structure which binds different types of dissolved organic matter for export. You run water through the carbon (ideally using a media reactor) to filter it. Alternately, you can place a bug of carbon in a high flow area like your sump/filter to achieve some of the benefits.

http://www.amazon.com/Marineland-PA0373-Activated-40-Ounce-1134-Gram/dp/B0002566WY

 

[srezack]

holy crap cant believe I didn't have this in my tank. so would it be more benefical before the biocube filter or after it? I think personally it would be higher flow after

 

[wpeterson]

There are different ways to filter the water for different thing. Most simple marine filters incorporate a mechanical filter (floss/foam) and some activated carbon.

Biocube tanks have an all-ine-one design with an in-tank sump compartment. What do you currently have for filtration and nutrient export? Many folks run mechanical filtration, carbon, and a skimmer.

Here's a link to some accessories showing how other folks have setup their biocube in-tank sump compartment for heating and filtration:

http://www.shop.mediabaskets.com/Biocube-29-Media-Basket-BC29MR.htm

This diagram shows the second chamber being used a media compartment, with racks for holding different filtration media like a bag of activated carbon.