SPS & Refugiums

[JohnV8r]

@Randy: I don't mean to thread jack my own thread, but - WOW - you really peaked my interest with this comment relating to one of the reasons why you keep three refugia:

to provide a place for aerobic bacteria to grow consuming the vinegar I dose

I dose vodka into my sump because I believed when I began dosing that dilution prior to entrance into my display tank was the most important factor for safe vodka dosing. Your comment about dosing into the refugium has made me question whether I would be better off dosing the vodka into the refugium directly instead of into the sump. Here is a bit of information before you answer that:

1. My refugium is fed from a tee off of my return pump. The refugium technically resides "upstream" from my sump, even though it is fed from water that has travelled through my sump. This old photo from when I set my tank up should help you visualize the flow:

2. The refugium has a capacity of 13 gallons. I calculate my net system with live rock at 194 gallons.

3. I currently dose .7 ml of vodka daily, which in concert with other filtration keeps my nitrates and phosphates at immeasurable levels.

4. I currently have a deep sand bed, chaeto, live rock, and lots of pods in my refugium.

5. The refugium is lit 24 hours a day with two 12" T5's (one 6500 & one 10K bulb) and produces a lot of very pink coralline algae that has spread in patches to my display tank.

My question is twofold: 1) Would I benefit from dosing the vodka straight into the refugium where the initial dilution would create a "hot" shot of carbon, potentially creating a more populous area of aerobic bacteria, and 2) would a "hot" shot of carbon or the increase in aerobic bacteria damage the chaeto, pods, or coralline algae?

Feel free to move this question into its own thread to avoid the blending the refugium/no refugium debate with the location of carbon dosing question if you want.

Thanks in advance. It just blows my mind how the discourse on this website can inadvertantly create opportunities to advance the understanding of certain nuances in this hobby!!!

 

[karsseboom]

Yeah 12 gallons on a 194 gallon system provide very little benefit it the tank if any. All the living creatures in that refugium is just for your own personal experience and may even be more harm then good in a strict ulns sps only tank. Your better off using that space to pack a bigger skimmer or a reactor.

 

[mc-cro]

I may have missed something but i dont see it being widely advocated to never clean your fuge.

Its not directly intended, but I would have to believe that is what ends up happening in reality. Lets put some common practices together here:

DSB: many people think that you are not suppose to siphon, stir, or disturb a DSB in any manner. Many people put a DSB in the fuge.

live rock rubble: live rock rubble is very beneficial for a number of reasons, but one of its drawbacks, especially in sand, is that it collects detritus

refuge flow rate: commonly the flow is kept extremely low through a fuge.

When you put this together, you have a very low flow area where detritus settles into live rock rubble and the sand bed. since people believe it is a sin to disturb the sand bed, they do not siphon, or move the live rock rubble to get to the detritus. Since they dont siphon or stir, exactly how would they clean it?

It would be interesting to take a poll and see how many people with a small fuge, or heck any fuge, actually take the time to siphon and clean it out every week.

Yes, growing some macro can certainly be a benefit, and a refuge can add some interesting biodiversity, but most, not all, hobbyist, do not take the time to think through the process when they have nutrient problems. Instead they start dosing carbon, adding denitrators, and other stuff to manage the excess nutrients that are still in the system. I personally have found that it is easier to remove excess nutrients rather than trying to manage them.

A skimmer, and harvesting macro does not remove all of the nutrients that you add every day. As Randy mentioned, most of the phosphates go right through the fish and other critters.

A study was done on various skimmer efficiencies, and it was found that even the "best" skimmers only pull roughly 30% of DOC's from the water column of a tank. Cheato and other stuff can only remove so much.

So, that stuff has to come out, right?

 

[jerpa]

I agree that people spend a lot of time adding equipment to solve problems caused by husbandry practices. Limiting nutrients into the system definitely reduce the need for export but that applies regardless of what method someone uses. You will have the same amount of detritus in a tank with or without a fuge assuming all other things are constant. You have to remove it from somewhere be it the fuge, DT, or sump. If you neglect any of them you will have issues. It may be that SPS tanks forgo the fuge because it's one less thing to clean.

My understanding is that most now believe a DSB should be left undisturbed most of the time but that you should replace a portion of it every year or so. A shallow sandbed should be siphoned or somehow cleaned regularly. I believe this applies no matter where the sandbed is located.

I think the problem lies in the aquarist and not the system. Someone sets up their refuge as an easy way to reduce nutrients, which it does, and never do the required maintenance. At some point it will turn into a nutrient source instead of a sink. I don't think this reduces the effectiveness of refugiums as a whole however.

 

[mc-cro]

I agree, as a matter of fact, that is what I said at the beginning of this thread, I just didnt expand on it enough I guess

there is nothing wrong with a refugium in the true definition, as a place free from predators.

the problem is that many reefers turn it into a sewer and just let food and detritus sit in there rot. there are no fish in there to eat the waste, so it just sits there and decomposes, releasing unused nutrients into the water.

 

[jerpa]

No my mistake. I thought you were implying they weren't effective at nutrient export period, not just when neglected.

 

[Randy Holmes-Farley]

My question is twofold: 1) Would I benefit from dosing the vodka straight into the refugium where the initial dilution would create a "hot" shot of carbon, potentially creating a more populous area of aerobic bacteria, and 2) would a "hot" shot of carbon or the increase in aerobic bacteria damage the chaeto, pods, or coralline algae?

Do you see nuisance bacteria anywhere undesirable? Some folks have such issues, and if so, dosing upstream of where you'd prefer the bacteria to grow is a good idea. I dose upstream from my refugia for that reason, and for the reason that I'd prefer bacteria to consume the vinegar I use rather than the display tank creatures, although I'm sure they get some.

But if you do not see problem bacteria in the main tank, there is no need to worry.

 

[JohnV8r]

Thanks for that! I do not have the bacteria bloom issue that some have. However, once in a blue moon I see a small patch on my sand. I think I'm going to start dosing in my refugium and see if I see any difference.

 

[Randy Holmes-Farley]

OK, that sounds like a fine plan.