Fish in cycling

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Krely

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Dec 10, 2014
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This is just to give everyone out there some information about doing a fish-in cycling vs fishless cycling. There seems to be a lot of confusion about the proper way (and yes there is a proper way) to do it. Some people will disagree with me, and that's fine, but I have done fish-in cycling with 100% success rate on both saltwater and freshwater tanks. There are pros and cons to both and I will list what I think are pros and cons for each.

This is just information on tank cycling. Patience is key to a long term successful saltwater system (you are recreating the ocean after all :))

Fish-in cycling

Pro: You get to add fish in almost immediately.
Con: A little more expensive at first
Must Must Must keep up with your WCs and check levels very closely

Filter advice: I try and get filtration that is double my tank size. Example: Get a 40gal filter for a 20gal tank.

How to do it:

1. Setup your tank as normal adding live rock and live sand (live sand is optional but I usually get a 10 to 20lb bag and mix with dead sand to create my sand bed). Mix or buy your saltwater and add to tank. (side note: If mixing your saltwater you will want to make sure you are getting close to the same levels every time you make it, ph, salinity, etc. This is very important and will insure success. Buying it has an advantage here as your LFS will almost always have the same levels every time, but mixing it yourself is cheaper)

2. I do this step, and have had great results, but it is optional. I use Bio Spira (an Instant Ocean product) when first setting up.

3. Wait 24 hours after adding Bio Spira to let the tank water go through the filter a few times.

4. Now add your fish. ONLY ADD 1 FISH for smaller systems. THIS IS VERY IMPORTANT. Get a hardy fish as well, a lot of people use Damsels and clownfish. If you have a bigger system (75 gal or larger) you could probably get away with 2 but I don't like to chance it.

5. Now for the most important part. WATER CHANGES, WATER CHANGES, WATER CHANGES. Did I say that enough times? WATER CHANGES. THIS IS KEY!!

You need to do AT LEAST a 25% water change BI WEEKLY. On smaller systems (30g or less) 50% would be even better. But at least a 25% water change.

6. Monitor your levels very closely. Daily until the cycle is done. The most important levels you are looking for while cycling is ammonia, nitrite and nitrate. With your water changes, your should be able to keep your ammonia levels low and when done cycling maybe 0. If you get a spike, and with using bio spira I have not had it spike high, an emergency water change may be needed in addition to the bi weekly changes, but I have found the bi weekly changes will keep your levels in check 99% of the time.

That's it. Be responsible, and on top of it and you can do it successfully with no harm to the fish I will add. And as normal practice, after the cycle has completed. 1 to 2 fish added slowly at a time ( every 2 to 4 weeks) will also ensure success.

Fishless cycling:

Pros: Cheaper (none to not as often water changes)
Easier as you really just wait and test parameters until you read 0,0,0.

Cons: Have to wait before adding first fish.

1. Setup tank as normal (Live rock, live sand, saltwater, etc)
2. Will need to add ammonia to start cycle. This can be done by either dosing ammonia into water, or adding some fish food, or a raw shrimp into the tank to start your cycle.
3. Monitor closely and when levels reach Ammonia 0, Nitrite 0, and Nitrate 0, for a few days consistently, you are ready to add fish.

Hope this helps some of you out there.
 
You forgot the biggest con to fish in cycling, your making an animal live in poison for your own enjoyment. It's cruel and unnecessary.


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I am so new to saltwater and before I jumped in this hobby, I read about fish less cycling. I cycled my tank without any fish and really enjoyed every step of the cycling process. Checking water parameters, seeing different nitrogen cycles and knowing that I am achieving the same without harming any fish. Fish less cycling FTW ... :)
 
This post wasn't intended to say which one is better or a right and wrong way to do cycling. This post was for information on how to correctly do a fish in cycle if you choose to go that route. I've done both and prefer fishless cycling as it's easier and cheaper and less time consuming.
 
Water changes only hinder the bacteria colony you are trying to create during the cycle by starving it of nutrients. Then if the fish live, you are stuck with damsels which in many cases, terrorize your other inhabitants and are nearly impossible to remove.
 
Actually doing water changes while the tank is cycling can help and sometimes can speed up the process (not by very much though).

From a chemistry standpoint: Oxygen is what the beneficial bacteria thrive on. During the cycle, as your ammonia and nitrite levels go up, oxygen levels get displaced, therefore the bacteria can potentially slow down production, as your BB requires oxygen and ammonia and nitrite to multiply. Therego doing a WC would replenish the oxygen supply and speed up the production of BB. And most of your BB gets attached to your sand, rock, and filter media, not in the water itself, although there is some BB in the water.

People recommend not doing WCs during cycling, others do just depends on who you ask, but most the time, doing a WC during a cycle doesn't hinder anything really, and if it did would not be much, but then again, your just talking a little bit of time.
 
"The surveyed reef aquariums divided into two distinct sets of husbandry protocols; aggressive and passive (see Fig. 6 for pictures of these aquariums). The aggressive husbandry practices included protein skimming, GAC filtration, and regular water changes in an active effort to scrub the water of nutrients. The passive approach did not involve any of these procedures. Interestingly, the aquaria subjected to passive husbandry exhibited bacterial counts that fell within the range seen on authentic reefs; 200 - 1000K/mL. On the other hand, the tanks that "benefited" from careful attention to nutrient removal protocols displayed bacteria/mL counts that fell far short of these numbers; only 90-140K/mL. In addition to monitoring water column bacteria counts, the TOC (Total Organic Carbon, see Feldman, 2008) levels were examined as well. Not surprisingly, the tanks with "unpurified" water exhibited TOC levels greater than those seen with the skimmed/GAC-filtered tanks. The "purified" aquaria's TOC levels fall within the typical TOC range seen on authentic, healthy reefs (Feldman, 2008); the passively husbandry tanks were 2-3x higher."

Taken from here-
Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration — Advanced Aquarist | Aquarist Magazine and Blog

According to that article, it does make a substantial difference doing water changes.
 
Like any of it really matters. The tank will cycle regardless of how much water is changed. The main reason to change water during any cycle is replenishment of alkalinity which the bacteria use up during nitrification. This will help stop a potential ph crash in softer source waters.


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Removing the food source will certainly hinder the cycle. This is why you need to raise ammonia levels substantially during a cycle. Changing out the ammonia filled water is counter productive. remove enough ammonia and your bacteria colony may be lacking. This is why some folks see ammonia when they add fish.
I have never done a single water change until after ammonia and nitrite levels have zeroed out and have never seen ph issues nor had any other Ill effects.
 
Removing the food source will certainly hinder the cycle. This is why you need to raise ammonia levels substantially during a cycle. Changing out the ammonia filled water is counter productive. remove enough ammonia and your bacteria colony may be lacking. This is why some folks see ammonia when they add fish.
I have never done a single water change until after ammonia and nitrite levels have zeroed out and have never seen ph issues nor had any other Ill effects.


This is part of the problem I feel. There is no one size fits all method unfortunately. It's good that you have never suffered ph issues but this does not mean it can't happen. It definitely has happened.

I agree removing water may be counter productive during a fishless cycle, but the end product test of a fishless cycle should be a couple of days consecutive nitrification of >2ppm ammonia through to nitrate so for those that have ammonia issues when adding fish haven't necessarily followed instructions correctly or have added way too many fish all at once.

I would still stock slowly after a successful fishless cycle anyway. I have never done one though.


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One should stalk slowly after a cycle, no matter what kind you choose to do so you don't overwhelm the bacteria base that you have built up.
When you talk about ph issues, I would want to question why there is an issue with ph. Simply having a powerhead creating surface agitation should be cutting out enough CO2 and bringing in enough oxygen to prevent any actual issues with ph. A water change to solve such an issue just seems counter productive regarding the ammonia in the water during a cycle, which is why I never recommend doing them until you are done...though I also advocate towards using a cocktail shrimp in some pantyhose rather than using pure ammonia as sometimes math/measuring is hard for some and water changes and trying to measure out even more ammonia to dose to where you needs to be just gets too complicated. Applying the KIS effect is always in someone's best interest.
 
As stated above. The nitrification process uses alkalinity and creates acidity. The reduction in buffer and increase in hydrogen ions can cause ph to fall drastically in a system the is promoting extreme nitrification. Not necessarily an issue in most tap waters but waters that lack alkalinity in the first place are at risk.


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So you are replenishing the alk level with the water change. Ph does have ties with alk, but ph level should find a spot and stay there. The unknown would be where that will be and a common mistake in the hobby can be not understanding ph. This is why ph buffers can cause so many issues when tied in with chasing the perfect ph level.


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So you are replenishing the alk level with the water change. Ph does have ties with alk, but ph level should find a spot and stay there. The unknown would be where that will be and a common mistake in the hobby can be not understanding ph. This is why ph buffers can cause so many issues when tied in with chasing the perfect ph level.


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True enough but you are demanding a very high level of nitrification during a fishless cycle. This is when ph issues can occur and is one of the reasons why heavily stocked tanks that receive no water changes eventually see a decline in ph.

Probably less of an issue in reef setups due to the addition of crushed coral substrates and close attention to alkalinity but from a freshwater stand point fishless cycles can see a rapid decline in ph where there is inadequate levels of alkalinity in the first place.


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But this is all saltwater, there are limits to how far it can drop. Even then it can function without issues. A sudden drop or increase of any level in a running/established system can be a problem, but during a cycle it won't harm anything.
You are also correct when it comes to substrate. Many of the substrates we use are a natural buffer with our ph. So, the magic number is 8.3, with an alk drop you will never see it at 6, for example. A 'drop' really isn't much of a drop and would only be a worry in an established system for sensitive inverts that won't be involved in a cycle anyway unless a hitchhiker from live rock or something.
Then when it comes to FOWLR systems, most don't even think about testing things like alk compared to those of us with reef systems. In the reef, alk is probably the most important element to monitor.
 
But this is all saltwater, there are limits to how far it can drop. Even then it can function without issues. A sudden drop or increase of any level in a running/established system can be a problem, but during a cycle it won't harm anything.
You are also correct when it comes to substrate. Many of the substrates we use are a natural buffer with our ph. So, the magic number is 8.3, with an alk drop you will never see it at 6, for example. A 'drop' really isn't much of a drop and would only be a worry in an established system for sensitive inverts that won't be involved in a cycle anyway unless a hitchhiker from live rock or something.
Then when it comes to FOWLR systems, most don't even think about testing things like alk compared to those of us with reef systems. In the reef, alk is probably the most important element to monitor.


Yes I apologise. I am posting in a section I hold limited knowledge of but the thread was regarding cycling which is something that is attributed in both fresh and saltwater systems and I was focussing on the water change/no water change debate and why it is important to change water in other systems. I was just trying to point out that the variables in any system are so large that it's difficult to say that what may occur for one person will be the same for the next.

Me and a fellow member were conducting cycling experiments because the latter was adamant that water changes were unnecessary. She dosed 16ppm ammonia in one go as a set and forget but the tank only made it a week or so before the addition of baking soda was required.

You are right. None of it really matters in a fishless cycle.

I have seen posts where a small tank stocked with goldfish has seen a decline in ph to the point where the bacteria cease to function. The ammonia created up until that point was in the non toxic ammonium form because of the low ph so the fish were in no danger. What happened was, the poster did a water change which diluted the ammonia but due to the ph shift the ammonia that was left became toxic and was still high enough to kill the fish. The drastic change in ph wouldn't have done them any good in the first place.

You are right though, this is salt (which I realised later) and this issue is much less likely to be seen but the danger does still exist in systems. Better to be aware?

I will go back to my fresh friends now lol.


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