Water changes causing fish deaths

[Myrkk]

Why are you adding bicarb?
Fluctuating pH can kill fish.

It’s the only thing that seems to settle the issue. I monitor the pH whilst doing it and it stays at 6 which is the usual here. I’m therefore not entirely sure what it is doing, but it does help.

 

[Sleeveless]

I moved to RO/DI water. Was losing a ton of fish. Tons of trial and error and in the end came down to (most likely) how bad my well water is. There was bacteria in it. Tons of CO2 which when offgassed brought PH from 7 to 8.4 overnight. Then my water changes weren't often or big enough.

Now:

Weekly 50% water changes using RO/DI
Remineralize with Equilibrium and Fresh Trace
Establish consistent PH with Alkaline and Acid buffer combo

I also use Flourish for plants, but they are lacking CO2 so that is my next adventure.

My only issue now is PH still going from 7 to 8.2 overnight from the RO water with offgassing. Problem is, it doesn't jump until its added to the tank and agitated so there is still a stress factor event though my alkalinity is consistent 5 degree.

With adding CO2 for my plants, I'm optimistic my now 7 PH goal will stay that way as well. It will give me a solid base of control from the time I buy fish from the shop to intro into my tanks. Currently I don't have good means to adjust fish slowly from the stores 7PH to my natural 8.2PH so CO2 is my fix... May not be the best plan, but is an effective one.

P.S. Know my well is saturated with CO2 due to how quickly my DI media is used up.
P.S.S I'm just telling my story and what I've had to do so can empathize with your situation. I'm still learning a lot and this forum has been awesome helping me get through my ordeals. Stick with it and with the wealth of knowledge here you'll get everything sorted.

 

[Fishfunn]

I agree with other posters here; go get yourself an RO unit. It makes life so much easier, and the fish and plants love it.
I have another RO unit under my kitchen sink to make drinking and cooking water for me too. I put a post filter on it to add calcium and other minerals back into my drinking water.

 

[Magnum Man]

Yep, we are also a 2 RO household… the unit in the kitchen is part of a hot and cold water dispenser, and the other unit is in the aquarium work area

 

[Colin_T]

My only issue now is PH still going from 7 to 8.2 overnight from the RO water with offgassing. Problem is, it doesn't jump until its added to the tank and agitated so there is still a stress factor event though my alkalinity is consistent 5 degree.

That's not right. Water from a r/o unit has no KH to buffer the pH and the pH should be 7.0 even after off gassing. If the pH is going up to 8.2 after being added to the tank, there is something in the aquarium raising the pH. Or you are adding too much KH buffer but 5dKH shouldn't raise the pH that much.

Get a bucket of r/o water and let it stand for a week. Monitor the pH each day during that time. It should remain at 7.0.

To find out what item in the aquarium is raising the pH, take an item out of the aquarium and put it in another bucket of r/o water. Have a second bucket of r/o water with nothing in and monitor the pH of both buckets over a week. If the item from the aquarium is causing the pH to rise, you should see that in the bucket of water containing the item.

 

[Naughts]

It’s the only thing that seems to settle the issue. I monitor the pH whilst doing it and it stays at 6 which is the usual here. I’m therefore not entirely sure what it is doing, but it does help.

If the pH drops without bicarb, the KH must be very low. Water with low KH has few carbonates and bicarbonates. The addition of bicarb provides a KH buffer so that the pH doesn't drop dramatically.
However it is hard to use this without pH swings so continue with very close monitoring.

It also may be unnecessary. Other members (notably Byron) have used very soft acidic water with appropriate soft water fish without issue. They allow the low KH, low GH and low pH to stabilise naturally and the fish thrive.

 

[Myrkk]

Interesting Naughts. I think you may have the hit the nail on the head there. The water in Scotland is very soft. However, the issue is the water changes so it must be stirring something up. I *whispers* was recommended a water quality forum and popped on there. they have suggested something called old tank syndrome. So I’m busy reading up on this currently.

I’m also wondering if the house move caused the death of bacteria in the sand and as I do a water change this is releasing something as the sand is stirred up.

 

[Colin_T]

Old tank syndrome is where you don't do water changes for a while (usually months) and the pH drops while the nitrates go up. Then you do a big water change and the pH suddenly goes up and the fish get alkalosis (poisoning from a sudden increase in pH). If you do regular water changes, you should never see old tank syndrome.

If you have an aquarium that hasn't been water changed for more than a month, do a 10% water change every day for a week. Then increase it to 20% every day for a week. Then 30% each day for a week. Then you can do bigger water changes after that. You should also gravel clean the substrate every time you do the water changes, and clean the filter every month.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

 

[Sleeveless]

That's not right. Water from a r/o unit has no KH to buffer the pH and the pH should be 7.0 even after off gassing. If the pH is going up to 8.2 after being added to the tank, there is something in the aquarium raising the pH. Or you are adding too much KH buffer but 5dKH shouldn't raise the pH that much.

Get a bucket of r/o water and let it stand for a week. Monitor the pH each day during that time. It should remain at 7.0.

To find out what item in the aquarium is raising the pH, take an item out of the aquarium and put it in another bucket of r/o water. Have a second bucket of r/o water with nothing in and monitor the pH of both buckets over a week. If the item from the aquarium is causing the pH to rise, you should see that in the bucket of water containing the item.

I have. I took a ro sample in a cup and let it sit. After just 24 hours it raised to 8. Nothing else except the water. Did it also in my old qt tank and that didn’t even have substrate in it.

My kh remains 5 at all times after buffer added. PH still goes up. Only thing I can attribute it to is the CO2.

Since I’m gathering water now, I took a sample of the ro and then the Ro that is treated with equilibrium. Took pics of ph. The ro is 6 and treated ro about 6.8. I’ll post full report after 24 hours of each sample sitting.

 

[Fishfunn]

I have. I took a ro sample in a cup and let it sit. After just 24 hours it raised to 8. Nothing else except the water. Did it also in my old qt tank and that didn’t even have substrate in it.

I have an RO unit with a deionizer. I have a TDS meter that measures both the TDS after the RO membrane and after the DI unit. My water after the DI is 0 TDS. I just measured my pH, and it is 6.4 sitting in the 30 gallon container. It has been sitting in the container for almost a week.

I agree that something is amiss if your pH is 8. It sounds like your RO membrane isn't filtering too well. The membranes do get clogged up over time and depending on the water it is filtering. It is recommended that 70 psi be used to push water through the membrane, so I have a pump that creates the pressure for water to enter the unit. You may want to talk to an expert at an RO manufacturing business about your RO water.

I recommend talking to this company: AquaFX 407-599-2123
https://www.aquariumwaterfilters.com/

 

[Sleeveless]

I use a TDS meter as well. Without DI it’s about 14. With it is 0. The unit recommends 30 to 50psi. These two pics show pure RO and treated RO with equilibrium

Straight RO

RO with equilibrium and alkaline/acid buffer

 

[Sleeveless]

I have an RO unit with a deionizer. I have a TDS meter that measures both the TDS after the RO membrane and after the DI unit. My water after the DI is 0 TDS. I just measured my pH, and it is 6.4 sitting in the 30 gallon container. It has been sitting in the container for almost a week.

I agree that something is amiss if your pH is 8. It sounds like your RO membrane isn't filtering too well. The membranes do get clogged up over time and depending on the water it is filtering. It is recommended that 70 psi be used to push water through the membrane, so I have a pump that creates the pressure for water to enter the unit. You may want to talk to an expert at an RO manufacturing business about your RO water.

I recommend talking to this company: AquaFX 407-599-2123
https://www.aquariumwaterfilters.com/

And I hate you lolol. In a kidding way. That site has me eyeing a 300gpd system. lol.

 

[Fishfunn]

Ok, you got me confused about the pH jumping from 7 to 8 overnight.

I only mix tap water with my RO water, so I get the minerals I need from the tap water. People recommend a 60/40 mixture of RO/Tap water. I have been doing this for years with no issues.

 

[Sleeveless]

Ok, you got me confused about the pH jumping from 7 to 8 overnight.

I only mix tap water with my RO water, so I get the minerals I need from the tap water. People recommend a 60/40 mixture of RO/Tap water. I have been doing this for years with no issues.

Yea. I can’t mix tap. Y well water is really bad. It’s brackish water basically. I have to use Seachem Equilibrium to remineralize.

 

[Fishfunn]

Yea. I can’t mix tap. Y well water is really bad. It’s brackish water basically. I have to use Seachem Equilibrium to remineralize.

I looked at SeaChem Alkaline Buffer and it is really sodium bicarbonate, so your pH will definitely go up if you add that.

According to SeaChem, you have to use Alkaline Buffer along with Acid Buffer to get the pH you want.

Seachem - Acid Buffer

www.seachem.com

In order to adjust pH gradually, or if water is soft or not well buffered, use Acid Buffer™ with Alkaline Buffer™. When using Alkaline Buffer™ & Acid Buffer™ together to target a specific pH, utilize the suggested ratio chart.

HINT: First determine the amount of Alkaline Buffer™ needed for the volume of water. This should be determined based upon your desired alkalinity (KH). Then, divide by the number in the middle column to obtain the correct amount of Acid Buffer™ required.

Acid Buffer	Alkaline Buffer	pH
1	1.3	6.5
1	2.0	7.0
1	2.5	7.5
1	4.0	8.0