Should I Get A 40 Gallon Or 55 Or Two 20S?

[BeckyCats]

I have a 10 gallon tank at home. I got into this whole thing a little reluctantly but have discovered that I love it. The only problem is that 10 gallons is not big enough. Not for the fish that are in there and not for my imagination.

I got the tank to rescue a single female molly who was getting threatened with the big flush. Buuut, you know how it is with mollies: the one became 7 (6 fry survived). She had them on Christmas - her "gift" to us for rescuing her? Ha ha! Well, now that it is almost Valentines day, she's had another batch.

I've been keeping the tank scrupulously clean (the water quality AND the water parameters) but this is just too much. I've always intended to rehome the babies but if I relocate them to a larger tank, I'll be able to keep them until they get big enough to give to someone else. Anyway, I don't have to rationalize a bigger tank to you guys! You're on board already, I'm sure! Lol! The important thing is that I finally got my husband on board!

So, here's what I was thinking with the new tank:
LED lighting hood
Real plants
Molly-mom
Maybe a female molly-baby or 2
Various rocks and driftwood
Other fish that would be happy to live in my water (to be researched later)

Part of me is wondering if I should get two smaller tanks (20 or 30 gallons) so that I can put some marine salt in with the mollies - small amounts just to raise the pH and kh, which are lower than I've read mollies like, and keep tetras in the other since they like my kind of water. Although, I've also read that one shouldn't mess with pH and that mollies are hardy and adaptable and if they have been doing well for this long they should be okay. What do you guys think on that score? If they are likely to be fine, I will just get one bigger tank, ...

Which brings me to the question of 40 or 55 gallon? Is there much difference in the amount of work involved?

I have shrimp in the 10 gallon now. The mollies are leaving them alone for now, but I want a shrimp-only tank for their peace and comfort. So, the 10g is spoken for.

Thank you, anyone for your opinions!

 

[BaylorPerez]

with the 55 Gal, you would need to do bigger water changes depending on the fish you do decide to put in along with the mollys. It is just depending on the amount of occupants. With having 2 20s, it is double the work, and double the money used on either tanks. Plus you would have to be certain not to forget about one of the other tanks. And with the Mollys breeding, the bigger tank(55 Gals) would help if you are trying to breed mollys as they are known for being breeding happy. Same with Guppies. But you would be better getting the bigger tanks if you wish to breed them or sell the fry

 

[SherLar]

   I agree with Baylor. Although personally, I would go with a 75 instead of a 55. The space they take up is about the same as they're the same length, and the cost difference isn't that great.
   However, if you want different types of fish, separate tanks is the way to go. 

 

[BeckyCats]

No breeding! I am going to rehome all of the males and probably most of the females. Right now, the babies are still not showing whether they are male or female, so I am okay leaving them together for now. As soon as they start to show, they will need to go elsewhere. From what I've read, my adult female could still have several broods to go, even though she hasn't been with an adult male for months. Yikes! My plan is to deal with them as they come, let the fittest survive, and rehome them before they can mate with their mother or each other.

That's a good point about double the expense for the 2 smaller tank option. I did think about the double work for water changes and that is a concern. Maybe just the one larger is a better idea.

 

[Byron]

Most aquarists will recommend acquiring the larger tank generally, though there is value in having more tanks that are smaller.  But before deciding this, there are a couple of issues facing you.
 
First, like all livebearers, a molly female once impregnated can deliver several batches of fry without a male being present, what is termed superfetation.  A healthy female will deliver fry at 4-6 week intervals, and there can be up to 120 fry per batch with a mature female.  Unfortunately, the female fry themselves can be impregnated very early on, so by leaving the fry together you may be heading into more trouble.  I cannot recall how soon this occurs, but in the coloured species (guppies, platy, swordtails) it is before they get their colouration.
 
Second issue is the water for mollies.  Salt is not the issue, but rather the hardness from calcium and magnesium that is crucial to their well-being.  If you have soft water, you need to increase the hard minerals.  A better option than marine salt is to use a sand or gravel composed of calcareous mineral.  Obviously this will increase the GH (general hardness) and pH in the entire aquarium, so soft water fish should not be maintained in this tank.  However, mollies need space, and if you intend dealing with fry you will need even more space.  Not all will be eaten by the parent(s).
 
Byron.

 

[BeckyCats]

Uh oh. Is there any way to determine gender before maturity? I thought I read that as soon as the anal fins start looking different, that's when they have to be separated. Otherwise, I don't know what else I can do to prevent pregnancies. I can't give them each their own aquarium. The best I can do I think is to separate them as soon as they show any signs of gender. I could possibly give them away sooner, but I don't know if anyone will want them so small.

I thought about using a gravel or coral to increase the hardness of the water but my concern was that it would jump down again after every water change. Would that be more harmful? I read the marine salt would raise the kh and could be added to each water change. Is this incorrect?

 

[SherLar]

   You could increase hardness by crushing a few cuttle bones into smaller pieces and adding them to your filters, or hang them in a media bag. They'll dissolve slowly and ad minerals to your water. Replace as necessary.

 

[eaglesaquarium]

The easiest way to maintain harder water for species like mollies is a double layer approach.   
 
Layer 1 - automatically... This would mean using a crushed coral type substrate.  This will dissolve slowly into the tank (faster when the water becomes acidic, and much much slower with alkaline water).  This would help to maintain a more consistent water parameter than just adding additives during water changes.
 
Layer 2 - increase the hardness of the water you replace with every water change...  This can be done with marine salt (mollies are very happy in brackish conditions, but would drastically limit your possibilities for planting the tank, or adding future tank mates).  The alternative (and vastly cheaper option) is a bit of epsom salt (Magnesium sulfate). 
 
As Byron points out, calcium and magnesium are the keys to success with the mollies.  The crushed coral will keep your calcium levels up, and the epsom salt will do the same with the magnesium.

 

[Byron]

Both SherLar and JD have valid methods.  As someone who has very soft water (GH and KH are next to zero), and having had to harden water over the years for specific fish, I will offer some of my experience.  I assume you intend keeping the molly/mollies, so this will apply to the tank for them, in which you will not have other fish (except similar hard water species, if there is room...a 30g tank would be my minimum for mollies having fry).
 
As JD notes, a calcareous substrate is the easiest way to go.  I have in the past used dolomite, and if I were to do this today, I would use one of the aragonite/crushed coral mixes.  Aragonite contains magnesium as well as calcium, and crushed coral is pure calcium (or nearly so), so with aragonite in the mix you get a good substance.  And this will work for years even in soft water.
 
Another method is to add this substance (aragonite/crushed coral) to the filter, along the lines of SherLar's suggestion.  I have not myself used cuttlebone, so I would want to look into how significant this is by comparison.  The bag of aragonite/crushed coral fine gravel or sand is very inexpensive and as I say it lasts years.  Back in the 1990's I used dolomite (similar to aragonite), about three tablespoons in a mesh bag in the canister filter.  This buffered the pH (which is what it was intended for) but I've no idea what it may have done to the hardness.  I would suspect very little.  More recently, I used aragonite like this, and the pH went sky-high but the GH and KH remained close to 17.9 ppm which is only marginally above my tap water GH/KH of 7 ppm.  So this would not be anywhere near sufficient for mollies if your water is on the soft side.  Ideally (or actually, mandatory) you want a GH no lower than 10 dGH (180 ppm) but preferably higher, and up to 30 dGH (530 ppm).  So the substrate is really the only way to deal with this, though I don't know your tap water GH/KH.
 
To your question about water changes...no, this should make no difference.  Again, I don't know the initial GH/KH, but I have found that once an aquarium becomes biologically stable and established, it tends to maintain that stability through water changes.  At the very least, you could do smaller and more frequent changes, up to a point, though larger changes are always more productive (except in rare cases).  I may have more to suggest once I know the actual GH and KH.
 
The problem with using marine salt is that it adds sodium, what we consider "salt," and this is not particularly good for any freshwater fish (except when targeting specific disease issues).  Now, mollies do sometimes occur in brackish water in their habitat, but this is not the general rule.  And aside from this, the commercially bred mollies available in all stores are so far removed from their wild ancestors, and have been bred and raised in freshwater for decades, that there is simply no benefit in adding salt.  The US Department of Agriculture reports that mollies have been introduced (and are surviving well) in Montana, Nevada, California and possibly Florida, and this is in strictly freshwater.  Salt does interfere with the physiology of freshwater fish; you can find out more in an article I wrote that is online on WWM:
http/www.wetwebmedia.com/SaltArtHosking.htm
 
Byron.

 

[BeckyCats]

Hmmm. Maybe I should just rehome all of the mollies since I don't have the right conditions. The problem is, we are a family who adopts animals from shelters, and my kids think very poorly of people who give away their animals, and here I am talking about doing the very same thing. But I am just worried about the health of the animals and whether I can provide a good home. How long can can they live in soft water? Mom's been here for about 3 months and still seems fine. Is she on borrowed time?

If I did put aragonite/crushed coral mix as a substrate, are there other fish that I could keep? Would I just put down the substrate and then forget it or would I need to supplement the water change?

Oh, to answer your question about the specifics, these are readings that I consistently get:

Ammonia, nitrate, nitrite, always zero.

pH is tough to read specifically but it stays around 6.5 I think. I use api test and also litmus paper because the api test only goes to 6.0 and the litmus paper does the entire range. It has never gone into the 5 territory.

Kh according to the api liquid kit is also difficult for me to read. It says put in drops until the liquid turns from blue to bright yellow, but it never looks blue. It takes one drop to look pale yellowish and two to be bright yellow. The test strips usually show either zero or between zero and 40. I have two different brands of test strips, both of which give similar results. All 3 tests point to 0-30 ppm.

Gh usually looks to be around 50 according to tetra brand and not quite 30 with api brand. Again, the test strip colors are not spot-on.

Apologies for the long windedness. I wanted to give accurate info but my test results are never clearcut.
I asked a LFS employee once about adding crushed coral and he said in a tone that implied I had just said the stupidest thing he'd heard all week, "Not unless you want a pH of at least 9!" Is this true? That doesn't seem safe to jack up their pH so drastically. How could I do this in a safe way?

 

[BaylorPerez]

nitrate shouldnt be 0, so your tank may be in the process of making the nitrate. As nitrate is good til about 20Ppm, as that lets you know you have the bacteria in the tank converting the ammonia and nitrite down to nitrate, also it could be used as plant fertilizer if you have some planted aquatic plants in your tank.

 

[Byron]

Hmmm. Maybe I should just rehome all of the mollies since I don't have the right conditions. The problem is, we are a family who adopts animals from shelters, and my kids think very poorly of people who give away their animals, and here I am talking about doing the very same thing. But I am just worried about the health of the animals and whether I can provide a good home. How long can can they live in soft water? Mom's been here for about 3 months and still seems fine. Is she on borrowed time?
 

 
Individual fish can obviously vary, but inevitably they weaken and death will follow.  The minerals that are essential for the proper functioning of the molly's physiology are not present.  In mollies, the usual indications of water issues include shimmying, white patches (fungus), lethargy, fins folded, maybe increased respiration and/or gasping at the surface.
 

Ammonia, nitrate, nitrite, always zero.
pH is tough to read specifically but it stays around 6.5 I think. I use api test and also litmus paper because the api test only goes to 6.0 and the litmus paper does the entire range. It has never gone into the 5 territory. 
Kh according to the api liquid kit is also difficult for me to read. It says put in drops until the liquid turns from blue to bright yellow, but it never looks blue. It takes one drop to look pale yellowish and two to be bright yellow. The test strips usually show either zero or between zero and 40. I have two different brands of test strips, both of which give similar results. All 3 tests point to 0-30 ppm.
Gh usually looks to be around 50 according to tetra brand and not quite 30 with api brand. Again, the test strip colors are not spot-on.
 

 
Ammonia and nitrite are good, these should both always be zero (post-cycling).  Nitrate at zero is fine from the fish's perspective; are there live plants?  I would normally expect to see some nitrate, say 5 or 10 ppm, but with live plants this is not always the case.  Nitrate like ammonia and nitrite is toxic to fish, but with nitrate there is a much wider tolerance, but it should still be kept low and zero is certainly no problem.
 
The pH below 7 is not good for mollies, or any other livebearer.  pH is generally relative to GH and KH (I won't bog this down with exceptions) and a low pH usually indicates a lower GH and conversely.  Which is why raising the GH will raise the pH.
 
The Tetra GH/KH test kit I am not familiar with, I use the API liquid which is reliable.  Your KH API liquid test is probably correct, and one drop turns the colour to yellow [my tap water is the same].  So you have very soft water (the GH tests with the strips are in sync with this) with a low KH.  This means that over time, any aquarium will become more acidic in pH.  The natural biological processes (primarily the breaking down of organics by various bacteria, as well as respiration by fish, plants and some bacteria) will acidify the water, and the pH naturally lowers accordingly.  The KH if higher would work to buffer the pH.
 

If I did put aragonite/crushed coral mix as a substrate, are there other fish that I could keep? Would I just put down the substrate and then forget it or would I need to supplement the water change?

 
I asked a LFS employee once about adding crushed coral and he said in a tone that implied I had just said the stupidest thing he'd heard all week, "Not unless you want a pH of at least 9!" Is this true? That doesn't seem safe to jack up their pH so drastically. How could I do this in a safe way? 

 
As I said previously, the substrate of calcareous material will last for years, certainly well beyond the fish's normal lifespan.  I do not think water changes would be an issue, but if you do go down this road, you would take tests along the way to see just how it plays out.  Testing GH and pH immediately before the water change, then about an hour following, and maybe the next morning.  You would soon get a reasonable idea of things.
 
Crushed coral does raise the pH, a lot.  The problem is that it lacks the magnesium, so part of the "mix" is missing, and it is not a good buffer on its own.  When I used just half a cup of crushed coral in the filter on my 90g tank, the pH overnight went from 6.4 to 7.6 while the GH and KH remained zero.  I myself do not recommend crushed coral alone, but with aragonite so the magnesium is included.  I found dolomite excellent at this, but I used aragonite more recently when dolomite was unobtainable.  And yes, the GH and KH and pH will all be high.
 
Which means, only fish requiring harder water.  You mentioned tanks of 40, 50, 55 gallons, or two 20 g.  If you only want to provide a good home for the rescued molly, a 20g will work, with aragonite.  If you move up to larger tanks, and use aragonite to house the molly, other mollies and livebearers will work.  But soft water fish will have difficulty, some very much so, with this, so I would leave these out.
 
Byron.

 

[BeckyCats]

To answer a question above, I have 8 live plants in the tank.

If I keep the mollies, do I set up their new tank with 100% aragonite/coral substrate across the whole floor or mix it with standard gravel? Also, can I just put them in or should I acclimate them first? If acclimating is needed, what is the process? How long should it take?

 

[BeckyCats]

Just spoke to my husband. His vote is to keep molly mom and a few female molly babies. So, now I have to figure out how to set up their new home as soon as possible and acclimate them safely.

 

[Byron]

To answer a question above, I have 8 live plants in the tank.

If I keep the mollies, do I set up their new tank with 100% aragonite/coral substrate across the whole floor or mix it with standard gravel? Also, can I just put them in or should I acclimate them first? If acclimating is needed, what is the process? How long should it take?

 
OK, that answers the nitrate question.  Nothing to worry about.
 
I will assume there is going to be a new tank purchased, say a 20 gallon?  If you intend keeping the molly, a 10g will become very cramped quarters.  Female mollies can attain 5 and even 6 inches.
 
I personally would mix the substrates.  You can buy a very small bag of aragonite sand or small gravel.  This will be creamy-white in colour.  You could mix this with ordinary natural aquarium gravel, or with common play sand.  But here I will digress and suggest a more realistic habitat substrate, and that is pea gravel.  Sand is my choice for substrates because I have substrate fish like corys, loaches, whiptails, and these are better with sand.  But none of these will be present so you can go to a Central American river theme which is very natural for mollies.  The brown mixed pea gravel will probably work best, but there is also a black mix.  I had the brown in my amphibian setup and really like it.  Up to you, but put the aragonite on the bottom, and the other on top.  A chunk of wood, some varying sized river rock pebbles, and your plants.
 
Depending upon the pH, you may be best acclimating the fish.  The GH will not rise that much initially, but the pH if too great can cause issues.  When moving fish I always do a water change in their present tank, then you can siphon out water to fill half a pail, net the fish in, and then slowly add water from the new tank.  The difference in pH will determine the time to take mixing the water.  I try to have the new tank slightly warmer, or the same.
 
Byron.