pH is slowly rising

[Pylor]

Hello all, I'm wondering if someone out there might give me some insight as to why my pH seems to steadily increase over time. I'm using RODI water and mixing in seachem's equalibrium and alkaline/acid buffers to reach a pH of ~7, kH ~6dH, and GH ~8dH. I thought it might be the chemicals settling, but I let a bucket of mixed water sit for 48 hours and the pH was still the same. Putting the water in my tank lowered the pH from almost 8 to 7.8, but I have a feeling over the next few days it will continue to creep up. Here's what I have in the tank:

• 4 silk plants, all soaked for a bit and pre washed before adding them
• 2 old rocks I used in the aquarium years and years ago, back before I ever really tested for anything ever. They're bought from a fish store, and kind of a brown/white mix with swirling similar to a marble sheet cake
• Driftwood, small thoroughly boiled
• Rock, very small, very new, with a little java fern strapped to it
• PFS, bought from the local pool supply store. Rinsed pretty well (though probably not well enough) and I only put in about 1.5 inches
• marineland emperor 280 with the regular filter pad and a big bag of month-old purigen, along with a brand new biowheel.
• Fluval C4, with stock white foam, stock drip tray material, and a bunch of the flival bio media in the basket.
• A hydro pro 3 sponge filter

I've noticed a lot of brown stuff in the aquarium, it grew in the sand, got in the filters (mostly the fluval, see this post). I have no idea if that could have anything to do with it, it just looks like what people refer to as Diatoms in the sand but more slime-like on the plants. Whatever it is, my endler's and endler fry peck at it constantly, all the time. It stained my purigen a little as well as my bio media in the fluval.

 

[Delapool]

Out of interest did it creep up? All I can think of is to test the rocks with vinegar. At that ph and if the rocks are carbonate, they would need to be fairly reactive so vinegar should be a good test. How old is the tank? Does the slime wipe off the plants?

 

[Pylor]

It did creep up, it gets up to about 8 and holds steady from what I can see. The tank is still cycling so I've been doing small water changes every other day and adding back ~7 pH water (mixed from RO and seachem buffers). This has a temporary, small impact before it goes back up the next day.

I'll do a test on the rocks when I get some vinegar, the tank is a month and a half old, with fish just added last friday (June 28th). Those rocks were in an aquarium for 3 years before being put in a storage unit for 7 or 8, then boiled and added to this aquarium. Originally purchased at a pet store, here's a pic

Slime seems to have either come off the plants or been eaten by the fish/their fry (yes, I've had endlers a week and now have many fry). Here's a pic of some still left on the right side of the tank, it was worse on this area, and I've cleaned of the left and front of the tank

Any help is appreciated!

 

[Delapool]

Definitely worth testing the rock I think. Nice looking piece! To me it looks sedimentary so worth a test.

Is that white sand as the substrate? I'd also test a handful of that as well just in case.

Vinegar is a pretty weak acid but I think a good test just to check.

I think the tank is still settling down. Diatoms are meant to be self limiting and common for a cycling tank - it's only the sand that I'm not sure on if all the silicates will get used up or the sand somehow continues to supply silicates for the diatoms to use. I'm guessing that in most cases it gradually gets used up, diluted with water changes or filtered out otherwise more posts would appear regarding established tanks.

 

[BBradbury]

Your Tank

Hello Py...

You must have quite a time keeping the chemsitry of your tap water stable. Unless you must maintain a specific water chemistry to support rare fish, you don't need to worry about the specifics of your tap water. pH, hardness and these things aren't important to a successful tank.

Most, if not all of the fish you get at the pet stores will adapt to the vast majority of public water supplies. They have for decades. I keep large tanks of fish and remove and replace large amounts of water every couple of weeks and just treat the tap water to remove chlorine and chloramine and then it goes into the tank. The fish and plants do fine with just the water change. No other chemicals or testing of any kind is needed if you change enough water and do it frequently.

You're obviously good at the chemistry end of things, but I'm wondering if all your effort is really necessary.

B

 

[Fresh2o]

I agree with continued water changes to keep things stabilized. Not a fan of altering new water unless it is unsuitable for tank use.
You should determine the root cause of the pH boost. Could be the tap water or something in the tank. I would test the tap water straight from the faucet and again after it has set out for 24 hours. I would also take a sampling of your substrate and one of the rocks. Place them in separate cups with tap water. Let then sit over night and test the pH. The tap water that sat over night would serve as your control. If any on the test subjects have a higher pH then that is probably the culprit. I did not include the silk plants because they should be inert. Include any other objects in the tank in your testing that could be in question.
Hope this helps!

 

[Pylor]

I use RODI water that I mix with two seachem products, and the TDS before the mixing is 0, so I don't think it's anything in the water itself. I also mixed a bucket of water and let it sit for 2 days and it still measured the same as before the wait.

It's not really that much trouble tbh. I put a bucket in my bathtub and let it fill for an hour while I do other things. After that I pull the bucket out and cover it with a cloth for when it needs mixing. At that point it's just 3 measuring spoons, mix slightly with a fish net (just to stir the water), then add. Pretty simple.