Flashing from tap water? Or hard water?

  • We are currently upgrading MFK. thanks! -neo

Jayzao

Gambusia
MFK Member
Aug 3, 2010
360
1
18
Lost Wages
When I filled and cycled my new 100G I used tap water. After two weeks when the tank was cycled and my LFS thought it was safe to add fish I started stocking. I change out 10% 3x week as 20% is a pain because of the depth of my water returns and hose length.

On all changes I have been using RO water from the local water store. The last change I used tap water again and I have some fish flashing now.
Is this a response to the water hardness? Even though it was only 10%?
 
When I get home I will test again and post the results.
Last test PH was around 7.5 and Ammonia was zero and so was nitrite. Nitrate was around 20 ppm.
I know we have pretty hard water here in LV so I will check GH and kH.
My thought was Ich too or some other nasty.
The tank is tropical and runs warm so maybe some preventative instant ocean salt may be beneficial.
Maybe a TBsp for each 5G of water exchange.
 
Why are you doing water changes with RO water? Are you trying to soften it?

If you do enough of them with RO you will deplete the alkalinity and hardness in your tank, and any other electrolytes and such needed for fish to survive. That's why when people use RO water for fish they mix that stuff back in to a specific amount. Fish can't live in pure RO water long term.

Also depleting the buffers in your tank will cause massive pH swings and a low pH since the carbonate buffering is what keeps your pH from dropping drastically. Even if your fish can handle the pH swings your biological bacteria will die off due to it.

Your fish could be flashing for various reasons, but the fact that you've changed so much water out for RO may be an issue. You need to test your kH, gH and pH on your tank and make sure you haven't crashed it.

When you do water changes you should be mixing in water with about the same parameters as what's already in the tank. That's why most people suggest not altering water chemistry and just using tap water because it usually stays fairly consistent. The majority of fish can adjust to different gH, kH and pH than their natural habitat, but they can't necessarily adjust quickly to large changes in the chemistry of the water they're currently living in.
 
Thanks for the great info.
The water hardness has been pretty well maintained (by way of test strip) as I have quite a few natural rocks from the yard. But the information about the depletion due to RO makes perfect sense similar to humans drinking too much distilled water and becoming Hypervolemic hyponatremia candidates.

PH has remained stable, but high due to rocks and crustacean population but I will continue to test and start changing water using the tap.
My main concern with tap water was chlorine. Should I use a water treatment in addition?
 
Jayzao;4397609; said:
Thanks for the great info.
The water hardness has been pretty well maintained (by way of test strip) as I have quite a few natural rocks from the yard. But the information about the depletion due to RO makes perfect sense similar to humans drinking too much distilled water and becoming Hypervolemic hyponatremia candidates.

PH has remained stable, but high due to rocks and crustacean population but I will continue to test and start changing water using the tap.
My main concern with tap water was chlorine. Should I use a water treatment in addition?

Use dechlorinator.

I use API dechlor, but I've also used stress coat, prime and several others. Prime detoxifies nitrites and ammonia and can remove nitrates to an extent, but it smells really bad, so that's why I use API.

Calcium carbonate based rocks (like limestone) will maintain hardness and alkalinity to an extent, but put in pure RO they probably won't dissolve fast enough to keep the hardness and alkalinity up high enough. Plus your fish do need more than just calcium and carbonates.

I would also recommend finding a liquid test kit (I use API) to test alkalinity, hardness, and pH, because the strips are notoriously inaccurate. Really the strips are not trustworthy for most tests (ammonia, nitrites, nitrates etc) because they will degrade when sitting on the shelf, after opened, and can be faulty directly from the factory for that matter due to mishandling.

You can use RO water if you get something like Kent Marine RO Right to add the hardness and electrolytes back into the water. They also make something for alkalinity, but you can really use baking soda (being sodium bicarbonate it will raise your alkalinity (due to the bicarbonate) but not the hardness) , along with limestone based rocks in the aquarium.
 
MonsterFishKeepers.com