Nitrates and a cold water tank – 09/21/07
Hi,
<Hello Ross.>
A year and half ago, two students set up a 100 gallon, cold,
<approx. temperature?>
saltwater tank for my classroom as a project. Since those students have now graduated, I have inherited the tank.
<Nice. I will set up a similar tank in the future, too, in order to keep some species I see regularly in large subtropical-temperate systems.>
As a result, I'm not quite up to speed about all there is to do to maintain the tank. Currently, there is a Magnum 350 canister with Biomax, a protein skimmer, and, I believe they are called, bioballs (round, blue, spiky plastic balls). The tank had two scup and hake (along
with a few crabs) for a year. The nitrites and ammonia have been zero since the original cycling. Toward the end of the last school year, the nitrates started creeping up. I removed all the fish over the summer (just leaving two crabs) thinking that the bacteria would have a chance to take back control of the nitrate problem. Unfortunately, that didn't really happen.
I've now added a number of invertebrates to the tank because I want to use them in the classroom. The nitrates are really off the charts now.
<A number would be good…>
(nitrites and ammonia still 0 ppm). So I have a couple of questions:
1. If the ammonia breaks down to nitrite and nitrite breaks down to nitrate, what removes the nitrate?
<Anaerobic bacteria, but those primarily live in deeper sediments as well as inside of porous rock material. Anaerobic bacteria turn nitrates into gaseous nitrogen that leaves the system.>
2. What do you think created this problem?
< Nitrates are what accumulates when feeding the fish. Most proteins in the fish food are ultimately turned into nitrates. That’s no problem, can be handled.>
I can do a partial water change (which I have done) but it doesn't seem to get to the root of the problem.
<Of course regular partial water changes should be done in any tank (at least 5% per week), but a water change of 30% can only decrease your nitrates by 30%. As a consequence large water changes are expensive for marine tanks due to the costs of the needed salt. What you probably want is natural nitrate reduction (also known as de-nitrification). Possible options for you are (order of my preference in this case): DSB (deep sand bed), live rock (see below for more detail), a refugium with cold water algae, a small sulphur filter. Those can be combined. You also should optimise the output of your skimmer and clean it regularly. Some recommended reading:
http://www.wetwebmedia.com/nitratesmar.htm
http://www.wetwebmedia.com/nutrientcontrol.htm.>
3. Finally, one of the posts I read on your site said to use more live rock etc. But live rock etc. seems to be associated with warm water tanks, how do I go about getting it for my cold water tank?
<It’s not only bacteria that make the rock live. More recent studies come to the conclusion you also need all the other filtering organisms, critters like feather dusters and such to transport water inside the rock. Current and diffusion alone are not sufficient. Therefore, you’d need rocks from approximately the same temperature as your tank to have critters that can survive in the tank. I think most tropic critters would not survive, but that depends on the actual temperature.>
Do I need to add new Biomax?
<Am not a fan of such nitrate removers except for emergencies maybe. Of course new Biomax would remove nitrogenous compounds like nitrates, but it has limited capacity and if your nitrates are through the roof it will likely only help a short time until you need to get a new one.>
Can you simply buy the bacteria you need?
<Anaerobic bacteria will develop “by themselves” in an anaerobic environment. In contrast to nitrifying bacteria I think they are not sold in bottles.>
What can I do to reduce the nitrate levels?
<Hope the suggestion above help. I’d start with a deep sand bed (can be seeded with sand from the unpolluted sea) and some porous rocks (read about curing live rock) in addition to regular water changes.>
Any help would be appreciated. Thanks.
<Cheers, Marco.>
Ross.

Re: Nitrates and a cold water tank. Nitrates and a cold water tank, follow up – 09/21/07
Thanks so much for your quick reply.
<You are most welcome.>
Of course, after I sent the email I realized I should have told you the temperature of the tank and the number and amount of invertebrates. The tank does have a chiller. The temperature is around 66-68° F.
<Okay, thank you for the information. Tropical live rock creatures would probably not like these temperatures, it would be best to get sand and rocks at the coast.>
There are about 4 small sea stars, 5 brittle stars, eight hermit crabs, 3-4 sea urchins, one Asian shore crab, couple of snails. (there were some small sea cucumbers but I think they were eaten by the sea stars).
By the way, I live in the Boston area. I wanted the tank to be a close approximation of our coast so I could easily gather inverts and keep them for classroom use. For DSB (deep sand bed), should I just collect some sand from a local beach?
<Sand from an unpolluted beach is fine. While sand grains, which are coated with beneficial bacteria, and all sorts of tiny inverts are desirable, detritus is not. I would put a few pounds of sand in a bucket, fill the bucket with water, stir the sand, remove the dirty water and repeat until the water stays somewhat clear while stirring. In addition I would not add all the sand to your system at once, but prefer adding a few buckets at a time. Finally it would be good to aim for at least 4”/10 cm of substrate. See http://www.wetwebmedia.com/deepsandbeds.htm and the linked FAQs. Typically it will take some weeks until stable bacteria populations, that remove nitrate, have established in the anaerobic zones, but once the deep sand bed is active it can be very effective.>
When doing a water change, I guess I shouldn't vacuum deep into the sand bed as that might expose what anaerobic bacteria I do have to oxygen. Or am I misinterpreting that?
<You are absolutely right. Just vacuum detritus at the surface if necessary.>
I do have a little bit of macro algae (Chondrus crispus). I've only been leaving the tank light on for about 2 hours a day though. A year ago, when the light was on longer, we had a problem with undesirable algae growing. Remove the light, and the problem went away. Will more light help my nitrate situation?
<It could, if the Chondrus crispus is growing fast enough to compete with the nuisance algae for nutrition. I’m sure the invertebrates would enjoy more illumination, too. As soon as the nitrates are low again, chances are not too bad that nuisance algae grow is limited and a somewhat more natural lighting can be introduced.>
Thanks so much for the recommended reading. They were very helpful.
<Thank you for sharing your most interesting project. Marco.>
-Ross

Chiller Setting/Temperature Swing - 01/17/07
What in your opinion is the best temp swing for a chiller to be most efficient?  I keep my aquarium at 76.5 degrees.  When the aquarium heats up to 77 degrees my chiller turns on and runs for 11 minutes then turns off at 76.5 degrees.  Approximately 11 minutes later it turns back on at 77.0 degrees.  So is 11 minutes on and 11 minutes off a good cycle for the chiller?
<<A 2-degree swing is fine in my opinion...and will be less taxing on the chiller/more economical to operate to boot>>
By the way my aquarium temperature readings I am using are measured by a digital thermometer probe placed in the center and half way between top and bottom of aquarium.  I am not the chiller thermometer.......
<<...?>>
Thanks in Advance!
<<Happy to assist.  EricR>>

Now He's Chillin'!
Hey Scott, It's Garth
<Hey Garth! Howzit?>
Chiller all sorted out.
<Excellent!>
Well without getting a controller I now have my temp fluctuations down to within 0.5 deg C. woolah! All that I changed, was to put the outlet from the chiller in the sump (the where the inlet is) and it actually thinks its colder than it is, and this maintains a very constant temp in the main tank.
Prob solved so it looks...
<Doesn't it always seem that the tougher the problem is, the easier the solution is? LOL>
Ok well I bought 2 purple headed fire gobies the other day (about a week ago) have been in QT since.
<Love that word...Quarantine! And those are great fish! You'll love 'em!>
Now the 2 clowns (ocellaris) in the display tank... one of them had 2 spots in his main body. But have now gone after a 5 min.s FW bath for each of them. All seems good now.
<Super! Another simple solution that worked out fine! Good job!>
But should I wait another 4 weeks before I release the purples into the main tank to be sure white spot outbreak comes back, or will a 21 day visit in the QT tank (assuming no more spots on clowns) be ample? I hope this makes sense.
<Well, 21 days in QT is fine for the new arrivals...My favored approach to marine ich is the "fallow tank" routine, in which the fishes are removed to a separate tank for treatment, and the tank is left without fishes for about a month to cause the parasite population to "crash" for lack of hosts. Not 100% effective- but quite good, nonetheless...>
And will 2 banana wrasses be compatible with 2 ocellaris clowns, 2 purple headed fire gobies, 2 red and white coral banded shrimp, and 2 clams?
<I love Banana Wrasses (Thalassoma lutescens), but they can be predatory towards smaller fishes, such as the Firefish and possibly the clowns. I'd opt or a more "compact", less predatory wrasse, such as the Canary Wrasse (Halichoeres chrysus)-similar coloration, but no real threat to other fishes...>
Just don't want anything to pick on anything...
<Excellent approach...There's nothing worse than having to net a "nasty" fish out after the tank is all stocked!>
Thank you so very much. Cheers MATE!
<Any time, my Southern Hemisphere Fellow Fish Nerd! Regards, Scott F>

Chillin'
Hey guys... just a quick question
<Sure...! Scott F. here for you...>
PLUS thanks for all your great help so far!! well done
<We appreciate the kind words!>
I just bought a chiller (Resun) and it turns on at 26 deg C and turns off at 24 deg C. 2 deg C limits, not adjustable is this too much of a temp difference for a reef tank?
with: soft and stony corals,2 ocellaris clowns 2 Nemateleotris decora (purple fire fish) (about to come out of QT) some clams and  2 reg and white striped coral banded shrimp.
<Well, two degrees is an acceptable variation...I wouldn't want to see more than a two degree swing in temperature, if possible. A temperature controller hooked up to your chiller can help...>
How to these thermostat controllers work if I need one of these?
Does the chiller plug into it (even if the chiller is designed as a 'stand alone' unit?)? and the controller itself plugs into the main power (supply)?
<Yep...That's essentially it. You could use any of the off-the-shelf models available, such as the Medusa, which is also available in a two-stage model, which can control both your heater and your chiller....>
Thus a more accurate controller... so more stable temps?
<In theory, yes! Most controllers have a one to two degree "differential", but the accuracy should be pretty good...>
I live in Australia, so I'll have to find one down here... but am just curious as to what I need to do.
I have found one that is called "Nema" controller for up to 1/3 hp chiller or 1000W heating (this is fine size wise) 1 degree C accuracy. Remote titanium probe
<Sounds exactly like what I'm talking about...You're definitely on the right track...>
Or I can spend an extra 100 dollars and get one that has 0.1 deg C accuracy just after your opinion(s). Thank you very much for proving such a great site. Keep it up!
<Well, accuracy is good! If you can get a super accurate controller at a good price, go for it! Otherwise, the "standard" models are fine for most purposes...Good luck with your search, and thanks for the support! Regards, Scott F.>
Cheers
-Garth-

Chillin' (Pt. 2)
Thanks mate
<Glad to help!>
well its seems to be quite accurate the thermostat in the chiller, always switches off and on at same temps, but its the 2 deg CELSIUS differential that is concerning me. Should it?
<Well, I think it is acceptable to many animals, but I'd much rather see a smaller differential, if possible. If all other system parameters are stable, it should be of minimal concern, IMO...>
The chiller has a memory, so if its main power is shut off (via the controller) it will remember its previous temp setting.
<Nice feature!>
So all I will have to do it turn it to full cool (0 deg C) and let the external thermostat control the temp? In theory...
<Sounds correct, in theory...Do monitor carefully...>
and as for what you said it is "Acceptable" for what sort of fish or we talking:)?
<Many fishes which inhabit lagoonal areas and reef flats do see shifts in temperature, specific gravity, turbidity, etc. on a daily basis, so they are more forgiving than we might think. Again, I suggest that if the other environmental parameters are acceptable and stable, then a modest daily swing would be acceptable. Not ideal...But acceptable>
I'm planning on adding a pair of banana wrasses in the next few weeks, that should be ok, right?
<I have found these to be very durable, hardy fishes...>
Again thank you SO very much... you help me sleep at night with all the help you give.. haha
<Yeah...I guess my writing style does have that effect on some people, huh? LOL>
Take care, and until next time
-Garth-
<You, too, Garth! Stay in touch and let me know how this chiller works out! Regards, Scott F>

- Chiller Question -
Jason S here again. Thank you for your fast response about my lighting question. One quick question, I have a 1/4 hp Custom Sea Life in line chiller. I just installed a new little Giant 4 series pump. What happens to the chiller if the pump ever burnt out? 
<Depending on where your thermostatic sensor is located, it will likely continue to run until something breaks.> <<Will turn itself off... no worries. RMF>>
Is there any thing like a flow switch that anyone makes so that when the flow stops it will cut off the power to the chiller? 
<Not aware of any such item that would be adequate for salt water.> 
Do you recommend any maintenance to prolong the unit? 
<About once a year I'd remove it from the system and run some weak bleach water through it for an hour or so and then and hour of rinse water... can be done with a bucket and a pump, returning the water to the bucket. Leave out in the open air for a day or so and then reconnect.>
Thanks,
Jason S.
<Cheers, J -- >