[teaklejr]

Hello, I have a 90 gallon planted tank that has been running for about 8 years with zero problems up until about 8 months ago. Tank has a a medium load of low/medium light plants, about 8 Rainbow's, 6 Torpedo Barbs, Rupper Lip Pleco(aka Joe Pleco after Joe Flacco the Ravens QB) Brushmouth Pleco, Flying Fox2 and a Pinktail Chalceus(he's awesome and no aggressive at all) ehiem canister filters, Fluorite substrate and a big piece of driftwood, pressurized co2 system and PH monitor. I have not added anything in about 2 years. Prior to the last 8 months my co2 would run throughout the day and keep PH at 6.5 but over last 8 months it never runs and PH sits around 5.8-6.0. After a 50% water change the PH will go up to around 6.8 but by the next day it's back down again. I just tested parameters for ammonia, nitrites and nitrates and all are zero liked I expected.

Just can't figure out why after 7 years it decided to change and continue to have low PH reading. If it's nothing to worry about then great just wanted to see what the experts have to say.

I just recently started to get back into enjoying the tank, for awhile I was ready to sell it but could not bring myself to let it go. I've had a few of the fish the entire time and could not bring myself to give them away and have someone kill them for some stupid reason. Now I'm back at it and ready to add more plants and enjoy looking at the tank.

Any input would be great.

 

[nel]

Read about "old tank syndrome", I have the problem too. KH and pH are going lower and lower, you'll have to buffer it eventually. My tank is 10 years old and it's hard to get the KH higher than 2, it's dropping quickly. Check your KH, probably it's best to get it over 3 dKH. Simple RO water buffer will do the thing.

 

[Hilde]

I wonder if nutrients in your substrate have depleted. What is your substrate?

 

[amcoffeegirl]

RO water would bring it lower though right?
I would do another 50 percent water change in a couple days.
And again in a couple weeks

Bump: https://www.discusfish.com/learning-center/water/general-water-hardness-gh.html

 

[Hilde]

Have you thought of adding something like Crushed coral in the filter? Since it dissolves slowly you wouldn't get a yo yo affect.

 

[nel]

Not RO water, just buffer for RO water (well, they're mostly sold as RO water buffers, just buy something that will add some KH).

 

[Hilde]

Not RO water, just buffer for RO water (well, they're mostly sold as RO water buffers, just buy something that will add some KH).

I have read that using chemical buffers can cause a yo yo affect. Many use sodium bicarb or calcium carbonate to raise the gh and kh for when Co2 is injected.

 

[teaklejr]

Thanks for the reply's. On Saturday I removed the very old piece of driftwood and 50% water change, pulled a few old plants that were not doing good, vacuumed everything and then Sunday night did another water change and cleaned both filters. As of today the Ph has stayed right at 6.6(with no co2)which is great because before after water change the next day it would be in the 5.5-5.8 range. Going to wait till Saturday and start doing small water changes to see if I can get my PH back to around 7.0 then start back up with the co2.

I am thinking it might have been a lack of frequent enough water changes and possibly the old driftwood. That piece of wood was in a previous aquarium so it has to have been in water for about 11 years. Right now I am happy and was excited to get home to check the tank out. It's been a few years since I was excited to come home and check it out, now I am back at it and enjoying just staring at the tank. Might even go to a local fish store this weekend and see what I find.

Again thanks for the inout and once I get it straightened out I will post a few pic's and an update.

 

[Hilde]

I am thinking it might have been a lack of frequent enough water changes and possibly the old driftwood. .

More likely the wood. For it is used to lower ph.

I am going to try crushed coral in my filter to raise ph form 6.8 to 7.2. For I too want to inject Co2.