Refugium or bust?

[Figment]

I moved from Florida to North Carolina last year and had to sell all my freshwater fish and equipment (tanks included). I kept freshwater fish for several years and enjoyed it, but I'm looking get back into the hobby. I'm looking to advance to saltwater after I move into the house I'm buying in a few months. I've done a fair bit of reading, but the subject of plumbing always raises concerns and a few questions for me. I'm definitely afraid of leaks, though hopefully I can be cautious enough to avoid any accidents.

I understand most of the "how to" steps on setting up a sump and it seems like a solid idea in almost all cases. My recent confusion stems from the use of refugiums. Some people say they are necessary and others say they aren't worth the slow water flow. Obviously it must depend on the system in question.

So my question is, based on the information below, is a refugium necessary or should I use a wet/dry filter?

- Looking for 150+ gallons.
- Stocked as FOWLR (stock will start out low and slowly expand over the next 6-12 months)
- No major copepod eaters will be kept in this tank
- Will use a sump with a protein skimmer

 

[Ron Reefman]

A skimmer is more important than either a wet/dry filter or a refugium and I'd pick the refugium over the wet/dry if you have the room for a good size one. On a 150g tank I'd like to have at least a 30g refugium.

The wet/dry filter vs refugium is a false comparison as they do different jobs. The wet/dry does the same function that the live rock does, the ammonia, nitrite, nitrate cycle. The refugium takes the final result of live rock (or the wet/dry filter), i.e. nitrate, and uses it as food (fertilizer) for the macro algae which can be harvested by removing algae when the refugium starts to get full of macro algae. The refugium will also help control phosphates (algae food) and pH (by reverse lighting the refugium from the main tanks. Either system can also have filters/socks to remove particulate matter.

I hope that helps?

 

[wicz101]

I currently run a 40 gallon refug on my system which just short of 200 gallons. All the gross algaes grows in there and non in my DT. Adds water volume which assist in swings. Only have positive things to say about them, wish I would have gone bigger. wet/dry in my experence are a real pain and the maintainance required, is not worth the positive.

 

[RocketEngineer]

Use of a wet/dry in a reef setup is likely to cause more problems than it solves because it is overly efficient at converting ammonia into nitrates but no further. By comparison, most liverock will convert all the ammonia present in the system into nitrates well before the level of ammonia becomes an issue but also has the added benefit of converting nitrates back into nitrogen gas deep within the rock, thus eliminating nitrates as well.

The benefits of a refugium are determined by how it is set up. Unfortunately, there are three main goals with three different ways of setting up the refugium to match said goals but people try to combine them and just end up with a mess.

If you are using the refugium as a place to grow macroalage for nutrient removal, you do best having an empty space that is well lit and contains a ball of cheatomorpha that is tumbled to expose all sides to the light. The key there is that the "refugium" has just the cheato ball and nothing else.

If you are using the refugium for pod production to generate live foods for the tank, the space should have plenty of rock and some lighting so the pods can multiply and feed off of the algae that grows in that area.

If you are using the refugium to house a deep sand bed, the best setup is no lighting and plenty of flow across the surface of the sand to keep detritus suspended so it can settle elsewhere such as near the skimmer where its much easier to remove.

The bottom line is that a refugium is not required for any saltwater setup. It can provide benefits but needs to be set up according to which benefits its intended for.

HTH,

 

[Ron Reefman]

You don't 'need' to tumble Cheato. It may be helpful but certainly not required. BTW, mine don't tumble and they grow just fine.

And IMHO a DSB should be kept separate from a refugium. It isn't a required, but it's easier to work on if it's separate. And I think the DSB is MUCH less important than the refugium algae.

 

[Figment]

What function does a deep sand bed serve?

 

[RocketEngineer]

What function does a deep sand bed serve?

I use a remote DSB for nitrate reduction. In my case, the DSB is actually inside a 5 gallon bucket next to my sump with a lid and lots of flow. Because the sand is very deep, you get a progressively less oxygenated area within the sand which in turns causes the bacteria to switch from using oxygen as an electron accepter to using nitrogen instead. Since the most readily available source of nitrogen in that environment is nitrates, the bacteria end up splitting the nitrate molecule into pieces with the nitrogen ending up as a gas that then migrates out of the sand bed and dissipates back into the air.

The chemistry is fairly involved but the end result was my 125g system going from 40ppm nitrates that water changes never touched, to 0ppm nitrates in 3 months and has stayed there ever since. Its not for everyone or every setup but it does work as intended when used for a specific purpose.

 

[Figment]

I use a remote DSB for nitrate reduction. In my case, the DSB is actually inside a 5 gallon bucket next to my sump with a lid and lots of flow. Because the sand is very deep, you get a progressively less oxygenated area within the sand which in turns causes the bacteria to switch from using oxygen as an electron accepter to using nitrogen instead. Since the most readily available source of nitrogen in that environment is nitrates, the bacteria end up splitting the nitrate molecule into pieces with the nitrogen ending up as a gas that then migrates out of the sand bed and dissipates back into the air.

The chemistry is fairly involved but the end result was my 125g system going from 40ppm nitrates that water changes never touched, to 0ppm nitrates in 3 months and has stayed there ever since. Its not for everyone or every setup but it does work as intended when used for a specific purpose.

From what I've read, it sounds like algae and DSBs serve the same purpose, but algae also tackles other nutrient problems as well. Is one better than the other for a FOWLR tank?

Could you combine the two as I've seen several people do with algae on top of their DSB?

 

[RocketEngineer]

Actually, they don't serve quite the same purpose.

Algae serves to remove phosphates and some nitrates. Using one type of algae in the refugium to remove phosphates starves the algae in the display so it can't grow. In this case, your goal is limiting phospates to limit algae in the display.

By contrast, a remote deep sand bed (RDSB) is eliminating nitrates in large volumes. If phosphates are well controlled but nitrates are very high, algae growth won't be able to bring down the nitrate level. Since nitrates can inhibit coral growth and at high levels is harmful to just about everything, it may be a situation where nitrate removal is more important than phosphate control. That's where a RDSB comes in and does the job.

Combining the two only causes problems, mainly for the RDSB, because the algae will send roots into the sand bed. These then allow a path for oxygen to enter, eliminating those low oxygen zones that allow the RDSB to remove nitrates. Also, the lighting the algae needs can cause the sand to become solid due to coraline algae (same stuff on the glass) cementing the top of the sand together. This blocks flow to the lower levels of the sand bed. Remember, the idea is to have low oxygen, not create an area of no oxygen. Either way, they really don't work well together and you can end up with problems on both fronts.

Now, let me explain my setup. I have a true refugium that I use to grow several types of algae in. By periodically removing most of the growth in the refugium, I'm removing the nutrients the algae used to grow from the system. Combined with lots of snails and hermit crabs, my display doesn't have a whole lot of hair algae. I also use a Bucket DSB which sits to one side of my sump. This is used for nitrate control and after several years of service, I still have zero nitrates whenever I test the setup. The point I would like to make is that they are each set up to do one job, not a hodgepodge trying to do both in the same volume.

Does that make sense?

 

[Figment]

Actually, they don't serve quite the same purpose.

Algae serves to remove phosphates and some nitrates. Using one type of algae in the refugium to remove phosphates starves the algae in the display so it can't grow. In this case, your goal is limiting phospates to limit algae in the display.

By contrast, a remote deep sand bed (RDSB) is eliminating nitrates in large volumes. If phosphates are well controlled but nitrates are very high, algae growth won't be able to bring down the nitrate level. Since nitrates can inhibit coral growth and at high levels is harmful to just about everything, it may be a situation where nitrate removal is more important than phosphate control. That's where a RDSB comes in and does the job.

Combining the two only causes problems, mainly for the RDSB, because the algae will send roots into the sand bed. These then allow a path for oxygen to enter, eliminating those low oxygen zones that allow the RDSB to remove nitrates. Also, the lighting the algae needs can cause the sand to become solid due to coraline algae (same stuff on the glass) cementing the top of the sand together. This blocks flow to the lower levels of the sand bed. Remember, the idea is to have low oxygen, not create an area of no oxygen. Either way, they really don't work well together and you can end up with problems on both fronts.

Now, let me explain my setup. I have a true refugium that I use to grow several types of algae in. By periodically removing most of the growth in the refugium, I'm removing the nutrients the algae used to grow from the system. Combined with lots of snails and hermit crabs, my display doesn't have a whole lot of hair algae. I also use a Bucket DSB which sits to one side of my sump. This is used for nitrate control and after several years of service, I still have zero nitrates whenever I test the setup. The point I would like to make is that they are each set up to do one job, not a hodgepodge trying to do both in the same volume.

Does that make sense?

Okay! That makes sense. LOL Thank you!

What size refugium do you use? Do you think I would have room for a skimmer, DSB, and refugium in a 75 gallon sump?

 

[RocketEngineer]

Honestly, I don't recommend a DSB in a main part of the system. The biggest benefit of it being in a 5g bucket to one side of the sump is that if it starts becoming an issue, you just turn off the pump and remove it. Its a lot harder to remove if its in the sump.

 

[Figment]

Honestly, I don't recommend a DSB in a main part of the system. The biggest benefit of it being in a 5g bucket to one side of the sump is that if it starts becoming an issue, you just turn off the pump and remove it. Its a lot harder to remove if its in the sump.

Do you have a picture of your DSB setup? It sounds interesting and it sounds like a great idea.

 

[RocketEngineer]

If you search Bucket DSB you should be able to find quite a few examples. Mine is just a salt bucket that I added a pair of 1" uniseals to. The inlet is supplied by a pump rated at 350gph and the outlet dumps straight into my sump. I used about 60 pounds of fine dry sand and even with the adjustment valve wide open the sand stays in the bucket. If I need to take it offline for whatever reason, I just unplug the pump and pull the bucket out of the stand. Not much to it.

If you want details on my specific setup, my build thread has a lot of the details.

 

[Figment]

If you search Bucket DSB you should be able to find quite a few examples. Mine is just a salt bucket that I added a pair of 1" uniseals to. The inlet is supplied by a pump rated at 350gph and the outlet dumps straight into my sump. I used about 60 pounds of fine dry sand and even with the adjustment valve wide open the sand stays in the bucket. If I need to take it offline for whatever reason, I just unplug the pump and pull the bucket out of the stand. Not much to it.

If you want details on my specific setup, my build thread has a lot of the details.

Perfect! Thank you so much, Rocket! You've been amazingly helpful.:thumbsup: