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FAQs about Fish-Only Marine System Maintenance

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Related FAQs: Fish-Only Marine Set-ups, Fish-Only Marine Systems 2, FO System Set-Ups, FO System Lighting, FO System Filtration, FO System Skimmers, FO System Livestocking, FO System Feeding, FO System Disease, FOWLR/Fish and Invertebrate Systems, Reef Systems, Coldwater Systems, Small Systems, Large Systems, Marine System PlumbingBiotopic presentations

Are FO systems easier to maintain than having more diverse life forms present? Halimeda goreaui, Small Leaf Hanging Vine.

Small Marine Aquariums
Book 1: Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner

Stocking a 90gal SW Fish Only Tank and a Question about Lighting -- 10/28/09
Dear Sirs:
<<Hiya Julia'¦and no need to be so formal. We guys and gals all operate on a first-name basis here>>
I am new at this, so please be patient.
<<Ah! '¦much reading/learning ahead then>>
I have a 90 gal SW fish only tank. It has a built in return. I use a 175 wet/dry filter and a Vertex 80 Protein Skimmer, also a T-5 light (2 bulbs). It has about 100 lbs of live rock and 80 lbs of live sand.
<<Sounds fine>>
I have so far:
2 Pajama Cardinals
1 Sixline Wrasse
2 Ocellaris Clownfish
3 Blue/Green Chromis
The tank is 3 ½ months old. I would like to add the following:
1 Royal Gramma
1 Green Goby
<<Mmm, could be anything'¦Gobiodon rivulatus perhaps>>
1 Flame Angle
1 Foxface
Each addition would be 1 at a time about 3-4 weeks apart. What do you think?
<<The already established Sixline Wrasse will likely give the Royal Gramma grief (may even damage/kill the Basslet); otherwise I think you'll be fine>>
About the length of time the lights are on. All the books say 1 hours,
<<'¦!? I think you meant 10/12 hours here?>>
But the fish store says 6 hours is plenty for the fish only tank.
<<Mmm, no'¦not in my opinion'¦ Better to go with something close to a 'natural' tropical light schedule (10-14 hours, based on your viewing schedule)>>
And the reduction in time will help control the Algae growth.
<<This is rarely the case>>
I understand that in nature light starts low, peaks, and becomes low again.
<<Yep'¦a result of the Earth's rotation/the Sun arcing across the sky>>
My light system doesn't do that.
<<Most don't, though some semblance of this phenomenon can be obtained with special (read: expensive) dimming systems or by sequencing bulbs on/off>>
It is either on or off. The tank is in my great room, which is a little on the dark side. Can you help me with this?
<<If you have room to add more bulbs over the tank you can set these up with timers to come-on and go-off in sequence to 'simulate' a morning and evening event. And while I like a lighting setup that varies intensity re to at least provide the fishes some measure of warning before all goes dark '¦be aware this is not an absolute necessity>>
Thanking you in advance for your time and knowledge.
<<A pleasure to share'¦and let me know if this is unclear/you would like further clarification>>
Julia from Orangeburg, SC
<<Ahh! Julia, do also check out the marine aquarium club just up the road in Columbia (http://www.columbiamac.org/), lots of good folks with helpful advice. Cheers, EricR'¦ Also just up the road in Columbia, SC>>

High nitrite and nitrate 4/22/08 I have a 54gal corner marine aquarium, fish only setup. I transferred fish from an old tank to this new setup, which I now know was a mistake since the tank had not properly cycled. <The root of your problem most likely.> All fish died except a yellow tang and a blue damsel. <Honestly, the tank is too small for a tang.> The tank has now been running for a month with a Megaflow sump filter system. I used BioZyme to help start the biological filtration. <Dried bacteria cultures are not worth much in my opinion.> My problem is I cannot get rid of nitrites and nitrates. <Nitrate buildup is a common problem in FO tanks, no deep sand bed or live rock for nitrate reduction so lots of water changes are necessary. Nitrites could be due to the tank still cycling, not enough filter media, or overfeeding. In this case I would guess the tank is still cycling.> Ammonia was high but is now back to zero. All other parameters are in good range except for the nitrite and nitrate. <Sounds like the tank is still cycling.> I have done 2 sets of 15 gallon water changes a week apart. <Needs more, nitrite is very toxic.> I am starting to get some brown algae growing on the sand/glass. <Normal for a new tank.> I am just at my wits-end. I cannot get rid of the nitrates.. What do I need. <Nitrates? Water changes is the only thing to remove them. Nitrites require the proper bacteria to be cultured.> Many thanks., <Welcome> <Chris>

Fish Only Tank With Algae Issues! -- 06/07/07 I recently set up a custom acrylic aquarium for a client. It's a 1500 gallon (approx) racetrack tank built by ATM in Los Vegas. <Sounds sweet!> The tank has gone through the initial cycle (setup early Feb). Fish at the moment consist of: 1 Vlamingi Tang 1 Desjardin' Sailfin tang 1 Regal Tang approximately 7 Green Chromis 2 Blue Damsels 1 Royal Gramma 2 Percula Clowns Inverts are approx 40 Cerith/Nassarius snails and 1 unknown type of Hermit (brown). The filtration consists of the overflow filled with bioballs, an incredibly huge wet/dry, UV sterilizer, double canister with 50 micron filter, and a useless skimmer that either produces nothing or overflows within 2 minutes. There is no in between. There is also about 60 lbs of live rock in the tank (more will be going in tomorrow). Within the last week, large amounts of brown algae have started covering pretty much everything within about 4 days of cleaning. The side walls are easy, and the sand is being turned not too bad by the snails (another 100 are going in tomorrow), but the coral insert is being overrun. <Well, there may be some issues that are occurring that can prevent, or help diminish the algae problem if addressed. First, review the maintenance procedures for this system. What kind of source water are you using? Untreated tap water often contains excesses of compounds and nutrients that can stimulate algae growth, particularly the nasty brown varieties. If you're not already using RO/DI water to prepare your seawater, do consider switching. Check that source water for phosphates, nitrate, and silicates, all of which can contribute to algae woes if left unchecked. If you are constantly changing water (a good practice), but using untreated water (a bad practice), this simply re-fuels the algae each time. If you are already using RO/DI treated water, do check your membranes to see if they need replacement. Also, consider the use of chemical filtration media, such as activated carbon and/or Poly Filter, to assist with the removal of organics. If the protein skimmer is ineffective, you really need to replace it with one that is. Protein skimming is vital, IMO, particularly in a fish only system. You need a skimmer that is both productive and consistent. Wet-dry systems, although effective, tend to accumulate nitrate because of their high efficiency. Water changes become more vital in a wet-dry filtered system. I'd consider yanking the bioballs at some point and letting the live rock do the "filtration". You may need to add more live rock, particularly in a system of this size. Another thought- replace that mechanical filtration media frequently, or it will simply become a nutrient sink as it traps debris and detritus if left unchecked for extended periods. Every couple of days is not too frequent, IMO.> My client really doesn't want to see the algae on the resin corals (it's the centerpiece for his entire entertaining area) and would like it cleaned up ASAP. <I can understand that.> What recommendations do you have for cleaning it naturally (by critters) or an easy way to get to it manually? <as above- you really need to address the root causes of the algae outbreak, and attack the problem with aggressive nutrient control and export processes, as outlined above. Another thought: Is it possible to install a refugium somewhere in the system where you can grow and harvest competitive macroalgae? Refugia are an excellent adjunct to FOWLR systems.> I'm not positive on the number of snails that I should even be looking at in a tank this size. If you have recommendations on numbers and species it would be appreciated, or any other tips for looking after a tank this size. <Well, if you go by a "snails per gallon" mentality, it should be hundreds.> I'm currently doing a 20 gallon water change every two weeks which is probably a bit on the low size at least when the tank is stocked fully. <I think that you should be doing at least (gasp) 150 gallons every two weeks...Large tanks still should receive 10% water changes, IMO. Expensive, but it goes with the territory.> There are no tanks anywhere near here like this one, so I can't just go check out another one to get ideas. The manufacturer has been frustratingly absent on after sales service the moment they got paid. Regards, James Foley Thunder Bay Aquascapes <Well James, it's a tough, yet solvable problem. The system has some issues that can be addressed with hardware modifications/additions. Also, working on some of the aforementioned husbandry issues can help, too. With a little testing, tweaking, hard work, patience, and the passage of time, this tank can indeed become the showpiece that the owner intended. Do make liberal use of the resources on the WWM site for more ideas on nutrient control and export, husbandry, and hardware. Good luck! Regards, Scott F.>

Fish Only Tank With Algae Issues (Pt. 2) - 6/7/07 Thanks for the very prompt reply Scott. <You're quite welcome!> The source water is tap. We're blessed with good water here. No nitrates, phosphates, silicates, TDS about 100ppm. I only use RO in my 130 reef. All other saltwater and reef tanks are just tap, and no algae issues in them, so I'm pretty sure it's more the setup than the water. <Okay.> I'll be calling ATM again today to try and get the skimmer working. It's plumbed into the system, so I'd much rather figure out how to get it working if possible. Changing it would be a royal pain. Underneath the stand looked very spacious until the drywall was put around it. :) <Lovely! It could also be an issue of where in the system the skimmer is located. If it's not situated where it will receive "raw", unfiltered water, such as from a surface skimming overflow, then it may not be set up for optimal performance from the get go.> About how much live rock should I be looking at for a final amount? <I don't buy into the "X" amount of rock per gallon idea. It's really a function of what you're trying to acheive. In a 1500 gallon system such as the one that you describe, it's entirely possible to get away with a relatively small quantity of rock (200-500 lbs, as you're contemplating). I was thinking in the range of 200lbs in the actual system as I'd like to keep sand area free. It looks quite nice with large sandy area. <Agreed. I like the open areas, myself...I've never been a fan of the "rock wall" aquascaping mentality that is so common in the hobby.> I have no problems adding a ton to the sump though. I will consider switching out the bioballs in the future. This is my first fish only system. I'm much more familiar with reef systems using complete natural filtration. <The good news is that you can apply similar techniques to FOWLR systems with a great deal of success. The big downer here is the apparently flawed protein skimmer. A skimmer in a fish-only system is a vital component, and it's proper function is vital to long term success. You really want to acheive a daily skimmate production to keep water quality high and dissolved organics to a minimum. The rock will act as your biological "filter".> Unfortunately the company tended to ignore my phone calls during construction, so I wasn't sure what the system was going to look like when it showed up. <That's a bummer...> There is enough room under the stand that I could probably put in a 30-35 gallon aquarium with Chaeto in it. Would that be large enough? It shouldn't be too hard to get it in there. <Hey, any type of refugium setup is better than nothing. With good lighting and regular harvesting of the Chaetomorpha, you can achieve some nutrient export.> I'll shoot for around 500 snails and see how that works. Can you think of a species that would be more inclined to cruise over the coral inserts than others? The Cerith actually spend more time than I would have thought on the glass. I'm used to them staying near the bottom of the tank. <Interesting. I like Trochus and Turbo species, myself.> I'll also start increasing the water change (I was aware of how large they'd have to be when stocked, even if I didn't want to admit it, that's more water than my 130 reef tank contains) amount and try some chemical filtration. <Excellent practice. The higher volume water changes are really necessary from the start, IMO. Chemical filtration is a great idea.> What are your thoughts on Seachem's Purigen? I started using it myself yesterday in my livestock tanks, but don't have results just yet. :) <It's a great product if used as directed. I really like SeaChem products. You should also consider Poly Filter pads from Poly Bio Marine. They are another excellent chemical filtration media that is very effective.> Thanks again for the replies. <Glad to assist.> I'll start looking into making changes tonight when I meet with my client. I'll also be doing a complete test on the system tonight as well, so I'll get back to you on that later. <Hope to hear how it turns out!> Regards, James Foley <Best of luck, James. I'm looking forward to a happy ending for you and your client! Regards, Scott F.>

Fish only with live rock and Bristleworms   12/28/06 Dear Bob, <Hi Steve, Mich with you tonight.> I searched your web site looking for information relating to my aquarium, I have a 125 Sea Clear system II fish only tank part of the live-stock includes a Copperband Butterfly (read somewhere that he will eat Bristleworms). <Sometimes.>   Do Bristleworms cause any trouble to FO tanks?   <Generally no, unless you have a super big monster hanging out in there unbeknownst to you, even then questionable need for concern.>   I plan to make a homemade contraption to rid of these pesky pests, but again, not sure if its a huge concern to the fish. <No worries, they are not really "pesky pests".  They are harmless to healthy animals, act as beneficial scavengers, and should be left in the system.> Thanks. <Welcome!  Mich> Steve

Green Wolf Eel Blenny & Snowflake Eel  11/16/06 Dear Mr. Fenner, <Erin> I am new the Marine Aquarium hobby (~1.5 years) and your book, The Conscientious Marine Aquarist, has proved to be an invaluable resource for me.  I apologize for bothering you, but wondered if you could offer me some advice. <Sure> Thus far, I am guardian to a small, fish only, 30 gallon tank with a total of 4, so far very healthy fish.  Due to my inexperience and the costs associated with obtaining proper equipment, I have thus far resisted the urge to "upgrade" to a larger system.  However, I was recently offered a 90 gallon tank for free by a friend <A friend indeed!> who no longer has time to care for her 2 large tanks.  The tank has been slightly neglected and has a thick growth of hair algae, but otherwise it is in good shape with proper lighting, skimmer, filters, and powerheads, etc.  It is a well established tank that she has had for roughly 8 years.  My only real hesitation is that its inhabitants are a beautiful Snowflake eel that is probably 18-20", a green wolf eel blenny (I hope that's that accurate designation) <Congrogadus... actually a Pseudochromid, a Dottyback... but goes by a few common names... this is one> which is probably 12-15", an 1 large trigger.  They are all beautiful, and I do not want to take them on if I will have difficulty keeping them as healthy as they appear to be. <I see> Can you please advise me as to how difficult these creatures are to maintain, and if a beginner like myself will be adequately able to do so? <Mmm, should be fine as they are now... having grown up with each other... However, you will likely find it difficult to add much other livestock here. I would "take on" as is for now... and later consider whether/when you're ready to possibly trade in these fishes for another adventure/experience> Thank you very much in advance for any insight that you can offer. Erin <Welcome. Bob Fenner>

Reef to Fish-Only   4/14/03 Thanks for the response!<No problem>? I have a couple of other questions regarding switching from a reef tank to a fish only tank.<Shoot> Do I need to continue to add all of those additives still like calcium, magnesium - I was using SeaChem reef plus and reef complete- Or is none this necessary?<I don't see the need.  Normal water changes should be fine.> Is there any additives/ minerals I should add to a fish only tank?<Just a good 10-15% water change every week or two.>  I would imagine the reef buffer I have been adding to my water changes is no good anymore. I would also imagine I would just be using the standards test kits, testing for PH , nitrite , nitrate and ammonia. I guess what I am saying is I wont need my Iodine, calcium, magnesium test kits any longer. Do you agree?<I doubt they will be of much need, but may come in handy.  Best to plan for the unknown.> For lighting I was using a 440 watt PC kit- Would it be harmful to continue to use this kit with fish only or should I sell it and get a  some with less wattage?<This is fine.  There is a guy on Reef Central I think who has 400 watts over a 20 long.  Thanks Ananda for that info.> Thanks Ron<Glad to be of service!  Phil>

Water issue 07/20/03 Dear Bob, <Well not Bob, but one of his minions, PF> I tried seeking the answer to my questions on the FAQ list, but alas I could not.  Thus I am writing to you.  I have a newly established marine tank.  It's a 75 gallon oceanic with a crushed coral substrate.  I have a Yellow-Tail and a Domino Damsel.  My equipment consists of an Amiracle Wet-Dry filter and sump (MR-200), an Aquamedic T-Flotor 1000 protein skimmer, an Ocean Clear canister filter, and a Lil Giant pump that drives the water into the tank (3MDQ-SC).   The water we used to fill the tank was tap water.  We dechlorinated it and used Coralife scientific grade salt.  My problem is that my water's pH level is too low.  I've been adding Kent Marine super buffer to it once a day, about 1 Tbsp dissolved in tap water and added to the sump.  Two days ago I started adding Kent Marine Tech-M magnesium supplement.  As of today, here are my water measurements: pH = 8.0 (from a low of 7.5) NO2 = 1.6 NH3 = 0 KH = 15 The age of the tank is approximately two weeks old.  Now the guys at my fish store are giving me varying types of information.  The latest was to add the magnesium in order to facilitate the SuperBuffer. The fish seem to be ok, although the Domino Damsel has something on its left sideways fin (sorry for not knowing the proper term).  Their appetites are good and they do not seem to be showing any signs of stress. Whatever advice you have would be appreciated. Thank you. Tom MAIT (Marine Aquarist In-Training) <Well Maity, two weeks and the tank is still in the stages of curing. At this point your LR should be curing (and you should be using LR). While your tank is still in the setup stage, I would recommend removing the crush coral and replacing it with a deep sand bed. The DSB will not only help remove nitrates, it will also help buffer your water. Check here for more info: www.wetwebmedia.com/deepsandbeds.htm. If you're not using live rock, I would also recommend you read this and immediately change your setup: www.wetwebmedia.com/liverock1.htm . A lot of dechlorinators lower pH, are you buffering your top off water? Also, you should be aerating it for 24 hours before use, same with your tank water. Hopefully this will help, PF> WQ parameters Hi there, <Howdy> Great website, very informative. I have a quick question about Ammonia, Nitrate, and Nitrite readings. What are considered "safe" for a fish-only system? All the cheap home test kits have different detection levels, and they don't specify whether the results are as Nitrogen or not, i.e. NH3 vs. NH3-N. Please clarify this for me. <Zip, nada, zilch for ammonia and nitrite, and a few tens ppm of nitrate are about right. Bob Fenner> Thanks much. Tracy Manning

Re: WQ parameters Thanks for the quick response, but 20 ppm of NO3 as N equates to around 80 ppm of NO3 as NO3 - which one are we talking about here? <The latter, which the vast majority of kits measure. Bob Fenner>

New Tank Questions Dear Mike D<Hi again> Thanks you very much for your quick reply.<You're welcome>  Your answers put my mind to rest as I thought my tank was heavily infested with some sort of parasite.<Understandable as the cycling process can be mystifying when first beginning.> Nevertheless I will keep my tank empty till the nitrite is undetectable.<Excellent and thank you!>  I purchased about 5 pounds of LR today as you recommended.  I'll give up surgeons until I get a larger tank.<Another very good decision. I suspect that eventually you'll end up truly enjoying this hobby, even with the bad beginning.>  Again, thank you.<You're VERY welcome> Asma

I recently wrote you about me upgrading my 125 FOWLR to an 180 FOWLR. My equipment consist of a 25 watt UV, MAK 4 pump, Turboflotor 1000, Nuclear canister filter, Approx. 150 lbs. of LR. You stated that you would need to know what type of fish my tank would include to determine if the Turboflotor would be efficient enough. Here is a list of what I would like to have. Any other recommendations would be appreciated. Coris Wrasse  Dragon Wrasse Sohal Tang Naso Tang (2) Dusky Jawfish Harlequin Tuskfish Red Sea Sailfin Tang Assasi Trigger <The Turbo floater (I take it this is a 1000 model) should be fine... and if it were my system, I would probably just use this unit...> Haven't had any luck with the large angel fishes I get them when there about 3 inches and they do well for about a week then they start to loose there color and die on me. I'm somewhat afraid to spend any more money on them. <Don't blame you... and the limiting influence may well be all these other fishes... really kind of crowded... psychologically if not physiologically...> With this setup and fish like this do I need to concentrate more on a better protein skimmer or adding a 30 gal refugium with LR? <The latter if not both> If both which one first, How many lbs. of LR should be in the refugium?  <the order stated, and about twenty to thirty depending on shape, density... and with Macroalgae and lighting... simple, on the sump.> Since space is kind of a concern if the refugium is added what I would do is connect my drains to a 100 micron filter bag at one end of the tank and have my protein skimmer next to it then my live rock, (would this be okay?) or does it need to be separate? <Can be together as stated> How can one tell if he has enough LR in a system to maintain it? Will a Dolphin pump be quieter and save me more money in the long run if I change pumps since I will have about 5ft of head pressure? Lots of questions but your assistance would be greatly appreciated. Thank You  <Measures of nitrate are indicative, and the Dolphin/other direct drive fractional HP pump, is a very good idea on all counts. Bob Fenner> 

Small Marine Aquariums
Book 1: Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner
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