water displacement

[Johny]

My wife and I bought a used tank a while back (partially stocked) and were told it was a 20 gal. Soon after I decided to measure and figured out its an 18 gallon, not a 20 gallon. Today I did a pwc. I use a 2 gallon bucket to vacuum into, and took out 3 buckets, or about 6 gallons. Should have dropped the water about 1/3 right? It was a lot closer to 1/2. This got me thinking that my decorations (several good sized rocks), gravel, filter and all have reduced it functionally to more like 15-16 gallons.

My question(s) : do I need to think of my tank as a 15-16 gallon tank regarding stocking?
Do any of you do this?

 

[jcolon]

I'd say continue to think of stocking in terms of the dimensions of the tank ... for a a couple of reasons.

1. Surface area ... This determines how well gas exchange happens and a 15 gallon tank would probably have different surface area than a 20.

2. Filtration ... You want a filter that can at least handle GPH 4x your tank volume ...though some members prefer 10x filtration (usually requires multiple filters).

Just my opinion on this.

 

[eco23]

It is something to be considered and is commonly overlooked. It's just another example of how the "inch per gallon" rule is not always trustworthy. It's also another reason that not overstocking is important.

The way I personally choose to stock a tank is by taking into account filtration capacity, dedication to water changes and tank maintenance, how quickly nitrAtes rise, swim room and most importantly common sense.

IMO, in most cases, if a tank seems empty to your eye, there are uncrowded areas of the tank (such as no bottom dwelling inhabitants), your water paramaters are easily maintained and nitrAtes are well within range, you are diligent with weekly pwc's and cleaning...you're probably okay to add a few more fishy friends.

However, there are a lot of variables such as the bio-load your fish produce (i.e. goldfish and Plecos produce a lot of waste) that also need to be taken into account.

Most importantly, hobbyists should use their experience and common sense. If a tank appears stocked or close to stocked...it usually is.

Great question, and another example of the many variables of the hobby many people take for granted.

 

[reefdiver]

Eco pretty much nailed it on the head. It all depends on the size, bio load and your maintenance.

 

[Johny]

Man... I can't tell you all how much I love this forum! Especially compared to the one I used to frequent. The people and attitudes are night and day. Thank you.

I kind of figured it would be a bit more complicated than just 18 gal vs. 20 gal. We have only been at this for about 2 months. We started out pretty naive (though not totally clueless, my wife and I both like to research before we do anything). I am blown away at the depth of knowledge and the intricacy involved in maintaining a tank.

I am guilty of not having a proper water testing kit. We hit a major financial...roadblock... before I had learned about them, so I cannot tell you my water parameters. I can say that I do weekly pwc's in the order of about 40-50%. I use a gravel vacuum and try and remove any food/poop I can see. I am careful about over feeding, and occasionally fast the fish. The inch per gallon rule always bugged me. We currently have 5 guppies, 6 glolight tetras and 5 black kuhli loaches. Inch per gallon, we are over stocked... but there is still a lot of empty space in our tank.

I certainly want to take good care out of my fish, but would like to get the most enjoyment from the hobby as possible. This has lead me to thinking about a lot of random things (like water displacement and its effect on stocking) and to research random things.

3 months ago if you asked I would not have thought keeping fish would be fun. I love it.

 

[tarpon]

a good thing to do to give the tank a more "full" feel is to have bottom feeders mixed with fish that swim in the middle of the water column, mixed with top dwellers. Fish at every level. Adds great dynamics. Idk what you can do about that now though with your current stock.

 

[tarpon]

And I also didn't have a water test kit on my first tank. But my fish were fine. You should get one when you can though.

 

[eco23]

Man... I can't tell you all how much I love this forum! Especially compared to the one I used to frequent. The people and attitudes are night and day. Thank you.

I kind of figured it would be a bit more complicated than just 18 gal vs. 20 gal. We have only been at this for about 2 months. We started out pretty naive (though not totally clueless, my wife and I both like to research before we do anything). I am blown away at the depth of knowledge and the intricacy involved in maintaining a tank.

I am guilty of not having a proper water testing kit. We hit a major financial...roadblock... before I had learned about them, so I cannot tell you my water parameters. I can say that I do weekly pwc's in the order of about 40-50%. I use a gravel vacuum and try and remove any food/poop I can see. I am careful about over feeding, and occasionally fast the fish. The inch per gallon rule always bugged me. We currently have 5 guppies, 6 glolight tetras and 5 black kuhli loaches. Inch per gallon, we are over stocked... but there is still a lot of empty space in our tank.

I certainly want to take good care out of my fish, but would like to get the most enjoyment from the hobby as possible. This has lead me to thinking about a lot of random things (like water displacement and its effect on stocking) and to research random things.

3 months ago if you asked I would not have thought keeping fish would be fun. I love it.

We're glad to have you as part of the forum, and you've already learned one of the most important aspects of the hobby...research

As you said, a quality test kit is vital. Once you have a tank cycled, stocked and up and running...the only things you should ever need are a bucket, a bottle of water conditioner (we all recommend Seachem Prime, it's cheap, super concentrated and efficient), fish food and a quality test kit. We mostly prefer the API Master kits. They run about $25, but they're pretty vital and will last you a long time. Strips are normally junk. You might as well guess what your levels are.

There are definitely a few tricks for newer people to the hobby that are not only cost saving...but also healthy for your fish. Never replacing filters until they are falling apart is one of the hints. To save myself some typing, check out the link in my signature. It's about fishless cycling (which doesn't apply), but there's a FAQ which gives some info about filter replacement and a few other things.

Hopefully by using a couple of the cost saving tricks, and not listening to the people at the pet store who will try and sell you unnecessary additives, you can more than make up the cost difference for picking up a good test kit

 

[Johny]

I've looked at the API master kits and I will probably go with one of those (as soon as I am able). About how long do they last? Say with weekly testing (or more if you should be testing more?) I saw on another forum that a good number of the members there didn't trust the readings on theirs past about 3 months. They were pretty sure the reagents had a short shelve life. Some recommended putting it in the fridge to extend the life, but even then said 4-5 months was the tops.

We did buy strips early on... and THEN found out that they are garbage. Oh well. I still use them every now and then just to see what they say. What else am I going to do with them?

I should clarify about saying that there is a lot of empty space in my tank. Its is not by any means empty, there just feels like there is still a little space there. Sometimes there are fish in all quarters of the tank, and sometimes 1-2 is all you can see.

 

[eco23]

There is a lot number on the API kits, and I believe the last 4 digits are the month and year they were produced. I can't remember the exact time frame they're good for...but 2 years is the absolute minimum before I'd even consider worrying. The only downside to the API's is that people read the instructions on the bottle without ever reading through the actual instruction booklet that comes with the kit.

For example, the nitrAte test is CONSTANTLY done wrong by people. The instructions tell you to shake the #2 solution bottle for 30 seconds, and the entire solution for a full 60 seconds, then let it sit for 5 minutes and record your results then. The bottles themselves however simply say "add 10 drops". So, when people don't take the time to read the actual instructions, they get readings ranging anywhere from 0-100 and then complain their test isn't accurate.

The API is absolutely the best bang for your buck, provides extremely accurate results (when tested properly) and last a long time.

I've actually emailed API suggesting they include more detailed instructions on the bottle...but lord knows if they'll actually take the advice.

 

[Terrance]

Just make sure all your fishes will not need more space than 15-16 gallons.

For my tank, I leave out the gravel to save myself a few gallons for the fishes. Of course, it makes the tank look a little unappealing to many people, but it does NOT make much of a difference for fishes. I get to keep more of my favorite fish in exchange for bad aquascape appearance. The good bacteria resides within my filter pad, hallow decorations, biowheel, and rocks (which I put in my filter system).

 

[tropical-fish]

The only downside to the API's is that people read the instructions on the bottle without ever reading through the actual instruction booklet that comes with the kit........

I've actually emailed API suggesting they include more detailed instructions on the bottle...but lord knows if they'll actually take the advice.

I couldn't get the API master test kit in my LFS so i got the individual test kits for ammonia, nitrite and nitrate instead. simplified instructions are printed on the back of the colour cards. shows the number of drops, how long to shake, time to wait etc. very handy as a reminder but it's always a good idea to read the full instructions at lease once before using the test kit.

 

[Johny]

Just make sure all your fishes will not need more space than 15-16 gallons.

Do you mean swimming room? Or do you mean in regards to their collective bioload? Or both maybe?

I believe that our LFS carries the API master test kit. It will certainly be the next thing we purchace/do to out tank.

Well...actually the very next thing is to figure out what to do with our guppy fry. We have six of them. We ended up with 4 males and 1 female (the adults). I know this isn't ideal. We pulled the female out and had her in a separate tank for about a week and she dropped her fry. Six survived. We are hoping that some (or all) of them might be females. That would do a lot to fix our male/female ratio. Problem is we would always have fry after that, and would probably need to add fish that would help cull the population. But then we would have a lot of fish in the tank... So yeah we will have to figure something out. I am hoping we are able to get the API master kit before any decisions need to be made so we can take our water parameters into consideration.

Does anyone know on determining the gender of guppy fry, do they all get born with the same fins and the males develop their gonopodium fin? Or are they born with it looking different than the female's anal fin and you just have to wait till they are big enough to see? I understand the difference in how they look, its just that all six of the fry appear to have an anal fin to me at the moment. I know it can happen to have all females, just not sure I trust our luck to have had that happen.

 

[Shadowraven]

While the amount of water in your tank will have some bearing, it only effects the amount of oxygen by volume that is present in the water. That very basic stocking guideline that you quoted is not actually based so much on the actual gallons, but on what the typical aquarium of a particular size can handle. It does not take into account the atypical tank that is higher than it is long.

The number of fish that an aquarium tank can handle is more a function of how much surface area is available. This is important for the exchange of oxygen and other gases in the water. The larger the surface area, the faster that this exchange will take place. So a 20-gal high only supports as many fish as a 15-gal long and will not support as many fish as 20-gal long.

The amount of fish a tank can handle is known as the carrying capacity. The carrying capacity depends on several different factors:

1) The amount and type of filtration that is used.
----The more filtration that is used and the greater its efficiency, the higher the carrying capacity becomes.
2) The type of fish or other animals being kept and the space available to them.
----a) Some benefit the tank more than others by cleaning up waste and acting in concert with the biofilter. (Catfish)
----b) Some are heavier bodied and require more oxygen then slimmer fish will. (Serpae Tetra vs. Neon Tetra)
----c) Some produce much more waste and stress the biofilter more heavily. (Goldifsh)
----d) Some fish have a much higher activity level and will require more resources. (Danios and Bloodfins)
----e) High activity fish require more space then their size would normally indicate. (Danios and Bloodfins)
----f) Some fish are very territorial and will require more space than usual. (Cichlids)
----g) Some fish are aggressive and some passive. A number of hiding places may need to be available. Each fish will need its own area to patrol.
----h) Some fish (i.e. guppies) can handle crowding much better than others.
3) The food being fed to the fish.
----Meaty, frozen and live foods will stress the biofilter more than plant-based will.
4) Whether plants are present and the lighting used for them.
----Plants aid in the uptake of nitrates from the water and become part of the biofilter, but are dependent on the light they receive for growth and health.
5) The amount of aeration used.
----Aeration in the tank will increase the amount of gas exchanged at the tank's surface.
6) The area available for nitrifying bacteria to inhabit.
----This is affected by the substrate used, porous rock, filter materials and other surfaces.
7) Tank maintenance.
----How often you vacuum the tank and do PWC affects how many toxins that are present in the environment.

The guidelines normally given of 1" of fish per gallon of water are just that, guidelines. The factors above also need to be considered when stocking the tank. I personally have always based my stocking on the amount of surface area in the tank rather then the gallons in it.

You should also try to base your stocking on a tank that isn't using aeration or multiple filters. You don't want to depend on these means. If you do and there is a power outage, it won't take long for the evils of overcrowding to become evident.

In an overcrowded tank, the amount of oxygen available is less per fish, so the overcrowded fish don't grow as well and diseases will often afflict them. For example, for many fish in this situation, their bones will grow faster than their muscles and they become deformed. Some fish actually exude a growth limiting hormone that keeps the others from getting too large.

A good place to get simplified stocking numbers that are based on surface area is by going to this page:

Aquarium tank volumes, capacities and stocking levels - US

I know that this throws a lot of information into the mix, but these are factors that should be considered when stocking an aquarium.

 

[Terrance]

Do you mean swimming room? Or do you mean in regards to their collective bioload? Or both maybe?

I believe that our LFS carries the API master test kit. It will certainly be the next thing we purchace/do to out tank.

Swimming room.

I found a cheaper API test kit online. I printed it out and Petco/Petsmart always matches the price

I try to get price matching for all my equipment.

 

[Johny]

1) The amount and type of filtration that is used.
----The more filtration that is used and the greater its efficiency, the higher the carrying capacity becomes.
2) The type of fish or other animals being kept and the space available to them.
----a) Some benefit the tank more than others by cleaning up waste and acting in concert with the biofilter. (Catfish)
----b) Some are heavier bodied and require more oxygen then slimmer fish will. (Serpae Tetra vs. Neon Tetra)
----c) Some produce much more waste and stress the biofilter more heavily. (Goldifsh)
----d) Some fish have a much higher activity level and will require more resources. (Danios and Bloodfins)
----e) High activity fish require more space then their size would normally indicate. (Danios and Bloodfins)
----f) Some fish are very territorial and will require more space than usual. (Cichlids)
----g) Some fish are aggressive and some passive. A number of hiding places may need to be available. Each fish will need its own area to patrol.
----h) Some fish (i.e. guppies) can handle crowding much better than others.
3) The food being fed to the fish.
----Meaty, frozen and live foods will stress the biofilter more than plant-based will.
4) Whether plants are present and the lighting used for them.
----Plants aid in the uptake of nitrates from the water and become part of the biofilter, but are dependent on the light they receive for growth and health.
5) The amount of aeration used.
----Aeration in the tank will increase the amount of gas exchanged at the tank's surface.
6) The area available for nitrifying bacteria to inhabit.
----This is affected by the substrate used, porous rock, filter materials and other surfaces.
7) Tank maintenance.
----How often you vacuum the tank and do PWC affects how many toxins that are present in the environment.
.

WOW! Thank you so much. I have actually seen bits and pieces of this information around as I have read through websites and forums, but that is definitely the most concise and organized I have ever seen it. It makes a lot more sense to me seeing all those factors listed together.

I have honestly been afraid to list my fish and talk about my tank set up. (here we go again... ) The last forum I frequented was VERY harsh when it came to helping people with their tank set ups. One person when so far as to suggest that people who overstock their tanks should have a rag soaked in ammonia draped across their face so they could empathize with the fish. Like I said, I want to take good care of my fish, but really? An ammonia soaked rag?

I will certainly take what you said into consideration as we move forward with our tank and fish.

Its also good to know that the chain stores will price match. I will definitely look into that more. This one expensive hobby at times. It would be nice to save a buck or two.

Thank you again all for your help.

 

[Shadowraven]

No problem. I am glad I could help.

BTW, don't be afraid to tell us about your setup. We are here to help you, not tell yell, criticize or berate you. You will find that most of us here are not too tolerant of mean-spirited or unhelpful people. The only way you will learn that you are doing something wrong is by constructive criticism and good advice. That is what we provide here.