Deep Sand Bed or Not?
- Thread starter Bearjohnson
- Start date
ohiojeff
Member
i run just a little sand. i cant say that i tried a deep sand bed. the reason is simple, todd at reefsystems helped me get things together when i was struggling, and he hates sand. i always advise newbies to find someone they trust and listen to them. the reason is that there are a lot of conflicting theories and opinions out there and it can get you crossed up. i also found that many of these differences often work for those using them. early in the thread many said either shallow or deep but in between is a mess. that is where conflicting ideas can bite you. i think many things can work well. my suggestion is to go with what works for you. i do a very shallow bed, enough to cover, and i like a course sand that stays put under my wavemaker. it is working for me, and i see no reason to move away from a system that is working.
theplantman
Active Member
Personally, I would expect a refugium that is planted properly with macro algae would reduce nitrates probably faster than one with a DSB. Algae love to soak up those nitrates and phosphates. I would use the chunkier substrate myself and make sure you have a pre-filter to remove solids before they enter the fudge, like a sock.
My sand bed is between 1.5 and two inches. I have the really fine sand.
I have never heard that sand beds between two and four inches are good. Why?
I have never heard that sand beds between two and four inches are good. Why?
Mike Johnson
Well-Known Member
That's exactly what I use, Mike. And after lights out my rocks and DSB are crawling with tons of life!
On a side note, my cerith snails laid eggs on the glass yesterday!
Carry on.
Gotta love it when the critters make babies.
This could be. The thing is, I don't know of anyone that's actually done a serious test, let alone a controlled experiment.
If I were setting up a refugium for myself, I'd likely go with course substrate and macro algae.
theplantman
Active Member
I was thinking the same thing, it would make for an interesting experiment. Although it would be pricey to set up. Two duplicate systems, stocked the same, fed the same, identical equipment and it would have to go long term I think so the deep sand bed could establish itself. The macro's would go to work right away.
It's been done already. I read It a few years back, 05-04?
I looked but can't find it.
Here is some good reading I did find on the topic.
http://www.reefkeeping.com/issues/2003-06/rs/feature/
http://www.advancedaquarist.com/2005/6/aafeature#section-8
Sent from my SGH-T999 using Forum Runner
I looked but can't find it.
Here is some good reading I did find on the topic.
http://www.reefkeeping.com/issues/2003-06/rs/feature/
http://www.advancedaquarist.com/2005/6/aafeature#section-8
Sent from my SGH-T999 using Forum Runner
Choff
Well-Known Member
I have heard this, but don't know why. Anyone? Why is 2 to 4 the bad zone?
Sent using Tapatalk 2
While we're on the subject, I'd love to know why also
Mike Johnson
Well-Known Member
Would love to answer this question; be prepared for a small article on the subject.
Mike Johnson
Well-Known Member
It's called passive nitrate control. The use of fine deep sand beds (DSB) and large quantities of live rock has made nitrate issues manageable or non-existent is many aquariums. This is because a complete nitrogen cycle can be achieved.
In a nutshell: Waste is mineralized by Heterotrophic bacteria to ammonium. Then Autotrophic bacteria, Nitrosomonas europaea, oxidize the ammonium to nitrite. Nitrite levels rise and Nitrospira-like bacteria (Autotrophic) multiply and oxidize nitrites to nitrates. Nitrospira-like bacteria grow at a very slow pace and populate slower than Nitrosomonas europaea. This is why the 6-8 week wait when starting a tank. Ammonia toxicity is the number one killer of aquarium fish; nitrite is number two. So far in this nitrogen cycle the fuel for growth of the bacteria is carbon dioxide.
This is where most of us are stuck - with high levels of nitrates. We can use protein skimmers, do water changes, and grow macro algae. I'm a proponent of all of the above. Attempts at making denitrifying equipment have come short because they have a tendency to create sulfide; sand beds in the 2" - 3" range can also. The topic at hand is why a sand bed above 1 1/2" and less than 3" can be detrimental.
To complete the nitrogen cycle we need to achieve denitrification by dissimilation, which is the breakdown of nitrate into nitrogen gas; which is done by bacteria in low oxygen zones (DSB's and rocks). Denitrification bacteria quickly uses up all available oxygen and are forced to use nitrates as their food or carbon source.
Nitrates can also be assimilated by growing algae and harvesting it. And, there is assimilatory denitrification, vodka and biodegradable polymers, which harvests the assimilated nitrates (and phosphates) through the use of a protein skimmer.
The optimal depth of a fine deep sand bed is 6". The minimum depth required for fine sand is 3". Aragonite has a half-life of approximately 18-24 months, it can dissolve at a PH as high as 8.2. Which is a wonderful benefit of having sand and the reason to make the sand bed deeper at the start. The dissolution of the calcareous sand is a source of minerals, like calcium and carbonates, for reef growth. These compounds are liberated when the substrate becomes acidified.
If the sand bed is under 3" in depth increasing levels of oxygen penetrate the sand bed and shifts the biological faculties from denitrifying to nitrifying colonies. Sand between 1/2" and 3" is usually not deep enough to reduce nitrate and yet too deep to be fully aerobic. The nitrifying bacteria in the oxygenated upper region of the substrate will compete with organisms for ammonia and other nutritive compounds in the water.
Thus, finally, the answer: The nitrifying bacteria will colonize in the sand bed, compete with organisms for nutrients (and win), and they will not be in the water column where they can be exported.
Any questions, I'll be happy to answer them. It's late, so, I hope I didn't cut it too short.
In a nutshell: Waste is mineralized by Heterotrophic bacteria to ammonium. Then Autotrophic bacteria, Nitrosomonas europaea, oxidize the ammonium to nitrite. Nitrite levels rise and Nitrospira-like bacteria (Autotrophic) multiply and oxidize nitrites to nitrates. Nitrospira-like bacteria grow at a very slow pace and populate slower than Nitrosomonas europaea. This is why the 6-8 week wait when starting a tank. Ammonia toxicity is the number one killer of aquarium fish; nitrite is number two. So far in this nitrogen cycle the fuel for growth of the bacteria is carbon dioxide.
This is where most of us are stuck - with high levels of nitrates. We can use protein skimmers, do water changes, and grow macro algae. I'm a proponent of all of the above. Attempts at making denitrifying equipment have come short because they have a tendency to create sulfide; sand beds in the 2" - 3" range can also. The topic at hand is why a sand bed above 1 1/2" and less than 3" can be detrimental.
To complete the nitrogen cycle we need to achieve denitrification by dissimilation, which is the breakdown of nitrate into nitrogen gas; which is done by bacteria in low oxygen zones (DSB's and rocks). Denitrification bacteria quickly uses up all available oxygen and are forced to use nitrates as their food or carbon source.
Nitrates can also be assimilated by growing algae and harvesting it. And, there is assimilatory denitrification, vodka and biodegradable polymers, which harvests the assimilated nitrates (and phosphates) through the use of a protein skimmer.
The optimal depth of a fine deep sand bed is 6". The minimum depth required for fine sand is 3". Aragonite has a half-life of approximately 18-24 months, it can dissolve at a PH as high as 8.2. Which is a wonderful benefit of having sand and the reason to make the sand bed deeper at the start. The dissolution of the calcareous sand is a source of minerals, like calcium and carbonates, for reef growth. These compounds are liberated when the substrate becomes acidified.
If the sand bed is under 3" in depth increasing levels of oxygen penetrate the sand bed and shifts the biological faculties from denitrifying to nitrifying colonies. Sand between 1/2" and 3" is usually not deep enough to reduce nitrate and yet too deep to be fully aerobic. The nitrifying bacteria in the oxygenated upper region of the substrate will compete with organisms for ammonia and other nutritive compounds in the water.
Thus, finally, the answer: The nitrifying bacteria will colonize in the sand bed, compete with organisms for nutrients (and win), and they will not be in the water column where they can be exported.
Any questions, I'll be happy to answer them. It's late, so, I hope I didn't cut it too short.
Akshay
Member
I have a deep sand bed too but it's a coral rubble mix.
The bottom most 1-1.5" of sand are filled in a net bag, which is never touched.
I only siphon the top sand and do patches every weekend, never the entire bed.
The patch is filled with sand from the sides.
The cleaned sand is scattered over the entire sand bed, to give it a fresh look.
The bottom most 1-1.5" of sand are filled in a net bag, which is never touched.
I only siphon the top sand and do patches every weekend, never the entire bed.
The patch is filled with sand from the sides.
The cleaned sand is scattered over the entire sand bed, to give it a fresh look.