Total dissolved solids revisited-- tds and test-kit comments

[Lorraine]

I am an avid TDS meter user, and it is about the only test I use on my tanks.
Wrights rule of 2x TDS works well for most fish but I have found diapterons to be much more sensitive.
Before the fishroom the diapterons were kept in 2 gallon tanks with sponge filtration, the TDS increases between water changes, I like a TDS of 100 for them, so I would make new water of that value. Removing 50% of the old water and adding the new, if I had been negligent of water changes which has been known and I tried to add the new water too fast the diapterons would start swimming upside down, sideways and lose their buoyancy, they could be resuscitated with the addition of higher TDS water and my finger under them keeping them afloat near the top of the water, in about 30 mins they would recover, fortunately I never lost one but certainly without the resuscitation I would have. This would happen with a TDS drop of 30 points done quickly. Also diapteron fry can die in a hurry with a water change done quickly, probably the same problem.
So with diapterons go really slow with the new water.

Fortunately mine are now on a central system with a large volume of water and drip to the tanks, so I don't have to worry any more.

[whuntley]

Lorraine,

Your mountain snow-runoff water that passes only over granite is most untypical. Probably 95% of US domestic water has some Ca and Mg and (particularly) K in it. If you feed bbs and other foods with a high Na content, any sudden change in your water could cause severe electrolyte imbalances. I wonder if that could be what hit your Diapterons?

When Barry Cooper moved out to Oregon, he ended up with water like yours, and I encountered the problem when I moved to Modesto. Mountain runoff over granite can be high pH and low tds (from silicates), with almost a total absence of the essential electrolytes that permit proper cell transport. We both solved our problem with addition of very small amounts of Seachem's "Equilibrium."

I initially tried to solve the osmotic pressure problem by raising tds to about 100 with plain salt. I nearly killed my fish and plants with that mistake. At a minimum, add some "No Salt" (potassium chloride) to keep the sodium from being lethal. "Equilibrium" has plenty.

Wright

[RonWill]

Lorraine,
When you said, "...and I tried to add the new water too fast the diapterons would start swimming upside down, sideways and lose their buoyancy, they could be resuscitated with the addition of higher TDS water...", are you certain that it's TDS differences that cause the fish to float I'm puzzled (actually d*mn curious) why or what causes this effect, so that I won't repeat the same mistake *.

If you feed bbs and other foods with a high Na content, any sudden change in your water could cause severe electrolyte imbalances. I wonder if that could be what hit your Diapterons?

Wright, would it have made any difference if I feed mostly daphnia and tubifex?

* I was doing regular water changes and lost 2 male 'Ekondo Titi'... both were floating and it was a heartache to watch them die, not knowing what else to do.

[TyroneGenade]

The bouyancy of fish is controled by the swim bladder. If the fish are floating this means the bladder has trouble---it has expanded to make the fish less dense. Ca and Mg concentrations effect the efficacy of muscles such as the swim bladder. A sudden osmotic shock could trigger the swim bladder to relax due to a sudden out-surge of Ca from the muscle cells' environment (Ca triggers contraction and Mg dilation).

It could also be a pressure problem.

tt

[RonWill]

Tyrone, could you repeat the explanation again, but in layman's terminology? I really want to understand this. Sorry to sound dense but thanks.

[TyroneGenade]

To contract muscles need Ca to enter the muscle cells. To relax the Ca is pumped out the muscle cells. Mg has the opposite effect. E.g. You tummy doesn't feel right, so you take some Epson Salts (MgSO4) and suddenly your tummy is working again... Mg causes the smooth muscle to relax.

The swim bladder is a giant hunk of smooth muscle. If internal levels of Ca and Mg are not right the muscle will malfunction... in the case of the fish, the swim bladder has lost its Ca and has now relaxed. So the fish is less dense (mass/volume) and so floats.

A slower water change well give the fish time to equilibriate with its environment. A fast water changes means all the minerals concentrated inside the fish are sucked out because of the giant soft water water change. The minerals simply flow out via the gills.

This is just one crazy hypothesis...

tt

[RonWill]

ok... I understand that much better but is there any way of reversing the damage or is it permanent?

[Lorraine]

iIt is reversible with quick action I believe. I added quickly some harder water, and supported the fish with my fingers, I hate to see them twisting and thrashing, trying to swim.
It took about 20 to 30 mins of this support (and dragging them through the water backwards when respiration stopped on one occasion) for them to start swimming normally. This has happend several time to my cyano pair. They are alive and well and happy.

Wright I can see your point on the sodium, I do feed BBS daily, although I rinse the BBS I'm sure not all the salt comes off.
I will try adding a touch of equilibrium for safety.

Do you know what effect the silica has on fish, do they feel it in the water?
I know that the diapterons have problems fertilizing their eggs when I used straight tap water, and the fry of several of my Aphyo's have problems hatching in straight tap water.

Now that I have the RO system with no waste water it may be worth my while serving all the fish RO with equilibrium rather than diluting with my tap water.

I was just thinking that my brackish fish don't have a problem with salt but then realized that I use instant ocean salt for them.