Low pH levels from unknown source

[huffie]

Recently have noticed that if I were to use my OH filter, the pH level will drop to between 4.5 ~ 5.0. Did a filter change, rinse my bio media with tank water, did a 10% water change and the tank pH level maintained at 6.0. After starting my OH filter pump the pH dropped to between 5.5 ~ 5.0 levels. NO2 and ammonia is 0 . Any suggestion or idea? My plants are in rockwool (which I think should be alkaline) as I do not have any substrates. TIA!

[Urban Aquaria]

Did you compare the pH effects if another different filter was used?

If you did water change, the pH of the incoming water (assuming its higher pH source) will mix with and adjust the existing pH higher slightly for a while, so you'll see a temporary change in the pH levels.

Since you didn't mention the use of any pH buffering soil or additives, then the constant lower pH levels could just be from an accumulated amount of decomposing organic materials (ie. plants, fish waste, food etc) in the tank and filter media. The active nitrification process by beneficial bacteria lowers pH.

[huffie]

Did you compare the pH effects if another different filter was used?

If you did water change, the pH of the incoming water (assuming its higher pH source) will mix with and adjust the existing pH higher slightly for a while, so you'll see a temporary change in the pH levels.

Since you didn't mention the use of any pH buffering soil or additives, then the constant lower pH levels could just be from an accumulated amount of decomposing organic materials (ie. plants, fish waste, food etc) in the tank and filter media. The active nitrification process by beneficial bacteria lowers pH.

U suggesting that I use other ceramic rings and bio balls or the normal white filter? So should I also be using pH bufferings like coral chips or baking soda? Lastly from what u described this is normal? Thanks again

[Urban Aquaria]

U suggesting that I use other ceramic rings and bio balls or the normal white filter? So should I also be using pH bufferings like coral chips or baking soda? Lastly from what u described this is normal? Thanks again

Well, most bio-media are inert so they wouldn't affect pH on their own... just wondering if you happened to use any special bio-media that may have had some pH lowering characteristics (would be good to check the descriptions of the bio-media you are currently using to see if they do).

Whether you should put coral chips or baking soda to buffer the pH back up depends on the fishes you are keeping, if they are those low pH or hardy adaptable fishes, then its not really necessary, putting additional buffers in a tank is a balancing act and can sometimes swing the pH too far upwards if not carefully monitored.

In a tank with no substrate (ie. barebottom) and no additional buffers, along with our local tap water being relatively soft and low kH, the pH of tank water will usually gradually decrease over time naturally as the bio-filter matures and the bacteria process more and more organic waste material (especially in tanks with high bio-loads).

One of the ways to reduce this effect is to do more tank and filter maintenance regularly (manually remove accumulated waste), do more water changes, or use products (like Seachem Purigen) which specialize in directly absorbing excess organic compounds even before the bacteria can convert them, thereby reducing the amount of waste being processed.

If you are keeping more sensitive fishes that require higher pH, then putting coral chips (or other buffers) can help maintain the pH higher, but you'll need to check the pH regularly to make sure its kept at a stable level.

[huffie]

Thanks urban aquaria for the explanations and advise. Actually the fish I have are "feeder fish" mainly for my son to enjoy. What I have is Tiger barbs and Platy. Previously had albino bristlenose, SAE and Otocinclus over period of different times and all doesn't survive long in the fish tank (don't know why, all sudden death).
Was thinking since rockwool are also "alkaline" could I use it instead of coral chips (since I have rockwool available from my workplace )? Many thanks.

[Urban Aquaria]

Rockwool is supposed to be biologically and chemically inert (from my experience using them to grow seedlings), so they shouldn't affect pH... unless the material had somehow previously been soaked with other chemicals beforehand.

I guess if you had fishes dying in the tank, the bio-load might have been too high and the waste material probably built up more than the tank can handle.

Just curious, whats your tank volume and the number of fishes in it? And whats your regular maintenance schedule like?

[huffie]

Size of my tank is 600mm x 450mm x 450mm (380mm water height). Started off with about 15 platys and about 12 tiger barbs with 2 otocinclus. Now left with 8 platy and 5 barbs. Change water weekly (~10%) with washing of washable filter.

[Urban Aquaria]

Platies and barbs do tend to produce a fair bit of waste, but their current numbers sound relatively moderate for that tank volume. If there are no more deaths and the fishes look healthy, then most likely the bio-load from the fish population has stabilized to a level that the tank and filter can handle comfortably.

I guess you could maybe try doing larger water changes to further reduce the potential build up of ammonia and nitrates.

[huffie]

Platies and barbs do tend to produce a fair bit of waste, but their current numbers sound relatively moderate for that tank volume. If there are no more deaths and the fishes look healthy, then most likely the bio-load from the fish population has stabilized to a level that the tank and filter can handle comfortably.

I guess you could maybe try doing larger water changes to further reduce the potential build up of ammonia and nitrates.

Noted thanks again.

[huffie]

By the way.. if Platies and barbs produce a fair bit of waste, would feeder gold fish be worse off? As I read that goldfish do produce quite an amount of waste also.

[Urban Aquaria]

By the way.. if Platies and barbs produce a fair bit of waste, would feeder gold fish be worse off? As I read that goldfish do produce quite an amount of waste also.

Yeah, i've kept goldfish before and their consumption and waste production is high, definitely more than platies and barbs, and they will eventually grow much larger too. You can still keep them though, just reduce the ratio of fishes to water volume to balance the bio-load (and do more tank maintenance).

[stormhawk]

If the water coming out of the overhead compartment is rather acidic then check the filter. If you have a lot of organic waste or detritus building up in the filter chamber, it will add on to the acidity of the water as the gunk continues to decompose. Feeder barbs and platies, if healthy and kept in a decent tank with good aeration and filtration, will survive for a long time. I still have more than 15-20 barbs from a bag of tiger barb feeders I bought for fun to populate my tank.

[huffie]

If the water coming out of the overhead compartment is rather acidic then check the filter. If you have a lot of organic waste or detritus building up in the filter chamber, it will add on to the acidity of the water as the gunk continues to decompose. Feeder barbs and platies, if healthy and kept in a decent tank with good aeration and filtration, will survive for a long time. I still have more than 15-20 barbs from a bag of tiger barb feeders I bought for fun to populate my tank.

Yeah even if I have replaced the filter, rinse the ceramic rings the water was still looming around 4.5 ~ 5pH.

[Urban Aquaria]

Whats the nitrates measurement in your current tank? That could help to gauge the amount of ammonia/nitrites being converted.

What type of plants and how much of them are in the tank? Perhaps a photo of the tank may help too.

Btw, to measure your pH, do you use chemical reagent test kits? or a pH meter?

[huffie]

The nitrates measured 0. I used test kit for measuring pH.plants dunno what they are but have attached a pic for ur ref

[Urban Aquaria]

If your test kits are not expired and working properly, then the measurements would indicate a cycled tank... though with the relatively low amount of plants in the tank and small water changes, its good that you are still able to maintain nitrate levels at 0 ppm.

Without an active substrate, i guess the only cause i can think of is just the biological process from the beneficial bacteria or perhaps there could happen to be some bio-media in the tank or filter which lowers pH further (i've read about some ceramic ring/noodle media which are designed to buffer pH lower, like Power House Soft Type). Can consider gradually changing them out in stages to see if there is any change in the effects.

Anyways, if the fishes are doing okay, then it means they have already adapted to the tank conditions.

[huffie]

noted