How much "bad stuff" do you actually remove during water changes...

[timmy82]

Mini cycles or incomplete cycles can be a royal pain in the backside ... hope you sort yours soon enough.

Just a quick word re salt and it's role in "controlling nitrites". Basically it doesn't do anything to the nitrites them selves, these remain available to the filter to be converted to nitrates. What happens is that the chloride ion latches onto the fishes hemoglobin where the nitrite ion would have, in effect replacing the nitrite in the blood with chloride. Nitrite stops the hemoglobin from transporting O2 around the fishes body, so the nett effect of using salt is that the hemoglobin maintains it's ability to transport O2 around the fishes body.

Using salt was the right call here. It does have other valuable uses in the aquarium too, but that is not for this thread.

Very good info Paul thanks for sharing. I don't want to hijack Toni's thread are you able to have a look at my thread oxygen injection and give some thoughts? Thanks

[strawberryblonde]

Hi Paul,

Thank you so much for the explanation of the action of salt on nitrites! I didn't think to add that and I do want this thread to be a sort of catch all, or reference point for future threads, so thanks. =)

I think I should also have added a calculator for the amount of salt to use.

[Second Hand Pat]

Toni, the proper use of salt, when and why would be most beneficial. Especically since there seems to be so much disagreement and deferring opinions on the forum.

[musicmarn1]

The first really comprehensive answer I've found on salt use in months of reading here! Thanks Toni! I will go read some of those studies too. I have never used salt, but I love to learn. That made total sense to me thanks

Interesting experiment. I'm doing 80-90 changes daily, I feel like I should do two BUT nitrite is more toxic than nitrate right, so if we are doing the same experiment with just crud and nitrate, is it still as important your saying?

If your discus has a skin irritation, as in flashing, scratching or twitching its fins, it's better to look at what is causing it, and then to correct the actual problem, than to add salt in the hopes that it will calm down the irritation.

Personally I wouldn't use it as a disinfectant in a fish tank! I'm not even sure I can think of an instance where you might use it this way. Can you give me an example?

Salt can be used for some external parasites, such as Ich, along with heat. It can also be used as a short term dip to remove excess slime coat. Those are both specific, extreme situations and it needs to be used correctly in both cases.

If you're up for some light reading, you might want to do some research, on credible websites...university sites, well respected fish expert sites, etc. to see what salt actually does when you add it to a freshwater tank. You might be surprised!

There is a delicate balance between a fresh water fish (especially discus) and the water they live in. Their bodies and internal organs are designed to operate at peak efficiency in plain water...without salt. When you add salt, you put extra stress on their kidneys as they try to regulate the change in specific gravity in the water. Do that often enough or for long periods of time and eventually the immune system will suffer as well as the kidneys.

[strawberryblonde]

The first really comprehensive answer I've found on salt use in months of reading here! Thanks Toni! I will go read some of those studies too. I have never used salt, but I love to learn. That made total sense to me thanks

Interesting experiment. I'm doing 80-90 changes daily, I feel like I should do two BUT nitrite is more toxic than nitrate right, so if we are doing the same experiment with just crud and nitrate, is it still as important your saying?

Hi Marnie,

You're right that nitrites are more toxic than nitrates. For just removing crud, poop and nitrates the one large water change per day is enough to do that trick.

The part that's important in all this, beyond what to do if you have a mini-cycle, is knowing that every water source has bacteria and other pathogens in it (molds, fungi, etc). It's unavoidable, and in small amounts our discus can handle them quite well. It's only when they reach high levels that they overwhelm the immune response of the discus and then they get sick, sometimes it's very sudden and death follows quickly on the heels of the intitial outward signs of illness.

Soooo, I guess what I'm saying is that this little experiment of mine showed me just how quickly pathogens can multiply in a tank full of discus and water! Bacteria and mold won't multiply as fast as nitrites, but they will grow out of control if the water changes aren't enough to keep their population to a minimum. Add higher temps for discus plus more nutrients in grow out tanks and without steady water changes it's a recipe for disaster, huh? =)

Have fun reading about the truly good uses of salt in a discus tank. There's a wave of forums and people out there who will say that adding salt everyday is just fine and even a good thing, but you know how that goes... say something often enough on the internet and it becomes a "truth"...even if it isn't actually true.

Salt does have its uses, but like any other med, it should be used wisely and with caution. For instance, here's a link to a salt calculator: http://www.fishtanksandponds.co.uk/c...t-nitrite.html

If you go to that link and click on the "volume calculator" link, you can find out your tank volume in liters. Then go back to the calculator and plug that number in. The result you get is the actual amount of salt needed to keep your discus safe from nitrite poisoning during a mini-cycle. Just FYI, it's not an exact science to convert grams to teaspoons, but 1 teaspoon of salt is about 3-4 grams.

So once you know the amount of salt to add, I'll go on to tell you that I've read on MANY forums that you should dose the tank at a rate of 1 tbsp. salt (about 9 grams) per 10 gallons for nitrites. The calculator says 1 gram per 20 gallons for 1.0ppm of nitrites. So they are recommending many many times more than is actually needed! And remember that when you add salt you change the specific gravity of the water. Discus regulate their internal gravity to match the specific gravity of the water. So when you change it, you stress their kidneys, etc as they try to regulate it.

Isn't it a fascinating subject? There's just so much science behind successful fish keeping and I'm a beginner. LOL

[nc0gnet0]

To expound on what Paul was saying:


"Diffusion occurs with a solute (in this case salt) migrating from a higher to a lower concentration in an attempt to equalize
the concentration. Once equalization is achieved, diffusion ceases. In the case of the discus, diffusion ceases when the
0.9% internal concentration equals the outside ambient salt concentration. Discus are constanly losing chloride via osmosis (along with urea etc) and as a result need to replace this lost chloride.


In order for the discus to maintain it's internal salt level (which it is constanly losing) it must pick up chloride, which it gets from background
salt levels in the aquarium water. Again, diffusion occurs across the gill lamellae via special cells, called columnar cells.
These cells actively seek out chloride ions; they also work against the concentration gradient, depositing the chloride ions
in the blood stream (i.e., from a low concentration to higher one).

The problem is that these cells although actively seek chloride ion’s, they are not that selective in what they pick up;
hence, they will pick up NO2 (nitrite) ions. So, what do we do if we have nitrite ions present? We simply out-number the
nitrite ions with chloride ions. The common statement about chloride ions competing with nitrite ions for entry to the gill
whilst gets the point across, is perhaps a poor choice of words in this instance, as it implies that there is some direct
conflict/ battle between the two ions taking place, the answer is far from being that complex,
If we achieve a ten to one salt to nitrite ratio in the water, the gill still has a ten to one chance of picking up a nitrite ion, which will occur if one comes into range of these special columnar cells in the gill.
An explanation?
Imagine you have a bag with 100 balls and 50% represent nitrite ions and the other 50% chloride ions, you have a
50/50 chance of picking up either a nitrite or chloride ion. Imagine the same mixture, but now the bag has 99 chloride balls
and only one nitrite ball, there is a one hundred to one probability of picking up a nitrite ion. Salt does nothing to alter
the toxicity of nitrite, just lessen the impact of nitrite by out-numbering the NO2 ions with the addition
of salt."

* Taken from Koiphen and slightly modified.


-Rick

[nc0gnet0]

Nitrite Toxicity (how/why is nitrite toxic?)


If the nitrite ions enter the blood stream, it oxidizes the hemoglobin to form methemoglobin - methemoglobin is absolutely
useless as an oxygen carrier. A hemoglobin molecule contains four sub-groups (haem- groups) also each haem- contains
ferrous iron, which gives the blood its red color and is also responsible for carrying oxygen. Each hemoglobin molecule
can carry a maximum of four oxygen molecules, or up to 70% of the amount of O2 held in simple solution in its
aquarium water at any given O2 saturation. When a hemoglobin molecule is exposed to nitrite, its ferrous
iron is oxidized by the Nitrite to form ferric iron. This not only changes the bloods color from red to brown
(brown blood disease), but it also alters the haemoglobin’s affinity for attracting oxygen and further is incapable
of oxygen transport.
The hemoglobin molecule is now known as Methaemoglobin, and this is the prime explanation for the toxicity of
Methaemoglobin. Once this happens, the hemoglobin molecule is finished, no amount of salt will repair this damage until
it is de-selected by the spleen and recycled to form new haemoglobin, but replacement by the spleen and kidney has
its own problems, because oxygen transport is now deficient – system’s which drive the
spleen and kidney to replace haemoglobin will detect this deficiency in Haemoglobin/oxygen, and will go into overdrive producing extra hemoglobin
to pull back the shortfall. The spleen/kidney cannot indefinitely produce excess hemoglobin if further nitrite poisoning
persists.
As haemoglobin production resources are used up by continual over production of haemoglobin, the fish will soon
die of anemia, indicated by pale pink gills. The best course of action for a fish that has already been subjected to high or prolonged exposure to nitites is methylene blue, not salt.

[strawberryblonde]

Thank you Rick! I had meant to get around to typing up the long explanation of why we use salt when nitrites are present, but time got away from me this afternoon. Came back just now to do it, and it's already done for me...you rock! =)

[lgomezvi]

This thread motivated me to run similar tests on my tanks after water changes. I am curious and not sure if I overlooked it but how are you able to determine your nitrate level so accurately? What test kit are you using, if you wouldn't mind sharing? I am using the API nitrate kit, but as you can see in the link below it could be flawed as I am not shaking bottle #2 long enough.

On reading about this topics, I found this old website that talks about myths about water changes. The information seems great and also poses some possible causes of mini-cycles. http://www.aquaworldaquarium.com/Art...er_Changes.htm Also has a spreadsheet to calculate required water changes.

HTH

[strawberryblonde]

Hiyas,

I was measuring nitrites, not nitrates. I use the API test kits for all my parameters.

I rarely bother to measure nitrates in my tanks because I change water every day, so they never have a chance to rise above 5ppm.

My mini-cycle was caused by the addition of my new batch of juvenile discus. I had seeded the sponge filter prior to their arrival, but it wasn't quite enough beneficial bacteria. Either that or I just squeezed the sponge too much when I was rinsing it in tank water. I rinse the filter once a week.