Converting from tropical Malawi cichlid tank

[mtreasure]

Hi,

I currently have several tropical Malawi cichlid tanks and have decided to convert one 200L tank to a fish-only marine setup, with just a few fish. I have a few questions and would be grateful for some help:

1. Will the existing freshwater bacteria all die when salt is added to the system?

2. I currently have coral sand in the bottom. Should I add some live sand to this, or is that not necessary?

3. Do I still need to add some bacteria to the water, even though the tank itself is over a year old?

4. Does the water have to be RO water. My tap water is fairly soft. Are there some hardy fish that don't need RO water?

5. I have some porous 'spaghetti' rock at the moment. I'd really like to keep this and it has been well cycled with the freshwater tank. Would it be sensible to just get one piece of live rock to mix with it, so that the 'life' spreads? Or do I need to scrap my existing rock and replace it completely with ocean rock?

6. I have a very substantial external filter. Will that be enough if I just get a few fish?

7. If I am not having coral, do I still need a protein skimmer? If so, why?

8. What easy, hardy brightly coloured fish would you recommend for a small community setup? I'd quite like some clown fish, and my kids obviously fancy a couple of Regal tangs, but I'm worried that they will get too big for this size tank? Is that the case? Are there dwarf varieties?

9. Do I need some crabs or shrimps to help keep the tank clean, or are they tricky to keep for a beginner? What is recommended?

Many thanks for you help - and patience with a keen beginner to marine. I hope that these are sensible questions...

MARTIN

 

[Alexander]

Hi,

I currently have several tropical Malawi cichlid tanks and have decided to convert one 200L tank to a fish-only marine setup, with just a few fish. I have a few questions and would be grateful for some help:

1. Will the existing freshwater bacteria all die when salt is added to the system?

Yes more than likely all bacteria will die, I would reccomend starting over, draining water and cleaning off any calcium deposits.

2. I currently have coral sand in the bottom. Should I add some live sand to this, or is that not necessary?

Live sand is very important, but if you have a substantial amount of live rock it will seed the sand

3. Do I still need to add some bacteria to the water, even though the tank itself is over a year old?

Adding liverock will add all of the essential bacterias you need to cycle your tank, you will need to wait through a cycle it won't be ready to go immediately no matter how long your fw setup has been up.

4. Does the water have to be RO water. My tap water is fairly soft. Are there some hardy fish that don't need RO water?

Sw dish are much more sensitive to water quality, and algae growth will thrive compared to a fw setup. I highly highly reccomend ro. Almost 100% of members here will use ro you will find.

5. I have some porous 'spaghetti' rock at the moment. I'd really like to keep this and it has been well cycled with the freshwater tank. Would it be sensible to just get one piece of live rock to mix with it, so that the 'life' spreads? Or do I need to scrap my existing rock and replace it completely with ocean rock?

You can keep this rock... it will be seeded with liverock when you add it, remember it will be best to empty it though and start over.


6. I have a very substantial external filter. Will that be enough if I just get a few fish?

It will increase work for you. Fi,lters need extremely regular cleaning as detritus collects and can become nitrate traps. I used one on my 80 gallon with a skimmer too. Worked great. Also can be a way of running carbon filtration.

7. If I am not having coral, do I still need a protein skimmer? If so, why?

You should definitely have one. Skimmers will work mostly with fish, as they produce so much waste. Corals need great water quality but produce minimal waste so if lightly stocked with fish you can get away without on a coral tank.

8. What easy, hardy brightly coloured fish would you recommend for a small community setup? I'd quite like some clown fish, and my kids obviously fancy a couple of Regal tangs, but I'm worried that they will get too big for this size tank? Is that the case? Are there dwarf varieties?

There are dwarf angelfish species, but not tangs.

9. Do I need some crabs or shrimps to help keep the tank clean, or are they tricky to keep for a beginner? What is recommended?

Crabs and snails. Unless you add fish that eat cleaer crew ex: puffers or triggers. Cleaner crew is very important for getting rid of detritus.

Many thanks for you help - and patience with a keen beginner to marine. I hope that these are sensible questions...

MARTIN

Welcome to the forum and remember sand will be less work and maintanence than crushed coral. Less space for waste to accumulate.

 

[Alexander]

Btw answers are edited in your quote if you missed it.

 

[mtreasure]

Thanks for the speedy reply Alexander. Your answers were extremely helpful. I just have a few more quick questions if you don't mind...

1. If you could recommend five or six different small community fish, nice colours and easy for a beginner, what would they be? Best in pairs?

2. Will live sand seed my existing porous rock, or is it essential to buy a few pieces of live rock?

3. Are starfish and shrimp difficult to keep?

Thanks again,

MARTIN

 

[ltljoker]

clownfish, dwarf angels if you add them at the same time and firefish can be great pairs. Also you can keep a school of chromis in a tank and some of them are quit brilliant in color. Some starfish are very complicated to keep, but a chocalote chip satrfish is one of the easiest ones if your gonna have a rock only tank, since its not reef safe.

 

[Alexander]

LT hit fish reccomendations right on. There are also gold head aka sleeper gobys that sift sand and are really fun to watch. But sand will be required. They do well in pairs.
Liverock carries soooo much biodiversity. You really should grab at least 25 % live rock in comparison to the rest of yourrock. Good rule of thumb too is 1 pound/ gallon of total rock is a minimum to go with. Unlike fw liverock is your main form of biological filtration.

 

[Bifferwine]

Hi Martin, and welcome!

You should drain the tank and start over with new water. Freshwater bacteria and saltwater bacteria are totally different. If you add salt to the freshwater setup, you are just going to have a lot of die off of the organisms that are already in there -- and that will pollute your new tank. So you are better off draining the tank, rinsing and cleaning it as best as you can, adding some sand, and adding new saltwater. You can re-use your old rock, but I would let it dry off first so the stuff on it dies outside the tank, before you add it to your tank.

You will need some sand or rock from an established saltwater tank to import the new saltwater bacteria into your tank. Do you have somewhere where you can get that?

 

[sen5241b]

1+ Bifferwine - drain it!

You may be able to find RO water at Wal-mart or at a Whole Foods market if you don't have money for an RO systems right now.

 

[dcantucson]

It would be better to start a new. You will be in control of things more.

 

[RyanG]

Martin,

As stated you should really drain your tank and start over. Your rock MIGHT be usable in a marine tank. When you have a piece out you should vinegar test it, if it bubbles than its alright for a marine system(this is the exact opposite of freshwater) That means the rock is calcerous(calcium based). Be aware that if you have treated you system with a COPPER based medication at any point in time than the rock shouldn't be used. Copper kills invertabrates and ,if you care to own, them corals as well.

 

[Bifferwine]

Good point about the copper. Copper is absorbed by rock and sand, so if you ever used copper in your tank, you will have to discard the contaminated rock and sand.

 

[mtreasure]

Thanks everyone for your advice. So would it be a good idea to take my Malawis out, salt the tank and run the filter for a week, to kill off all the freshwater bacteria, and then take out the water, clean the rocks and filter, etc. If yes, can I just use sea salt for this, or do I have to use special marine salt even though I will be removing all the water anyway?

Thanks again,

MARTIN

 

[Bifferwine]

I would do it differently -- I would just take all your freshwater fish out, drain the freshwater, then start it with salt. Clean your rocks and filter and put them in the tak. You don't need to fill it with salt twice. You will have to use special marine salt mix specifically for saltwater aquariums.