Getting Majorly Low Ph Readings. Why?

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Gage Zamrzla

Gage Zamrzla

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MFK Member
Jun 25, 2010
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Penn Valley, CA
Basically I got a large datnoid (10") and unexpectedly was given another (8"). They are temporarily housed in a 75g until my 125g is cycled, currently with 1 (7") and 3 (3"-4") dats and some clown loaches. I know my tank is overstocked, my 125g got delayed but is coming along and I didn't expect getting two large dats. My filtration is a Fluval Fx5 and Fluval 305 both filled with Efi Eheim and Biomax and have sponged on the intakes that are rinsed once a week. I also now have a Koralia 750 and 1400 aiming upward for surface agitation. I use black sand (doesn't altar Ph). Like I said, I wasn't expecting my 125g to take this long and wasn't expecting a second somewhat large datnoid and my tank had an ammonium (spelling?) spike with the obvious Ph drop. I did daily 10-15% water changes and added more biological filtration to compensate for the added waste and within a week and a half the ammonia reading completely disappeared and I continued to do daily changes for a few more days to be sure the ammonia was actually under control. I let the water sit for a few days and checked the readings again a few days ago and the ammonia is completely gone and my nitrates were steady, the Ph however was still very low (6.0) I did panic but my fish seemed just fine though they were less active than usual. I've done 20% water changes the last two days and my Ph is right around 6.8-7.4 but every day it enevitably sinks back down until it hits the low 6's. My water perimeters as of tonight are as follows:

Ph: 6.8-7.0
Ammonia: 0ppm
Nitrites: 0ppm
Nitrates: 20ppm

The Ph this morning was 7.6 so the drops have been less and less but I won't be satisfied with a temporary solution, I want to be sure why the Ph is dropping and fixing the problem at the source even if it means moving fish out before I have a home set up for them.

I recently thought the drop in Ph was because of a lack of oxygen in the water, all I had in the tank were two small brick shaped air stones. I took those out and got the Korelia 1400 and aimed both the 750 and 1400 at the surface going to the left (towards my Fx5's intake) in an attempt to increase the oxygen in the tank. Since I've done this the fish all are more active and seem to be eating more. Basically I got rid of the ammonia/ammonium, added bacteria, added more oxygenation and somewhat increased the Ph with water changes (tap water is 8.2). Am I totally wrong about low oxygen causing low Ph? I know I probably put a lot of info up and the problem may be extremely simple and I'm just being stupid but if anyone can help I'd appreciate it. I work in a fish store so by the time I come home my mind is so fish exhausted from dozens of customers tank problems that sometimes I let little obvious mistakes turn into bigger ones. One last thing, the only stuff I add to my tank is water conditioner (Kordon NovAqua Plus), aquarium salt (API brand), abd occasionally Fritzyme (Nitrifying Bacteria) after water changes so it's not like I add a whole lot to it. I do also have two medium if that sized pieces of driftwood and some rock (I'm positive it doesn't altar Ph) all of which were in the tank before I had any problems. Again sorry if I'm just being a weenie and it's an obvious fix.
 
I do not know, I'll get a text kit for that tomorrow morning. In the mean time, how would that possibly effect the Ph?
 
Well, basically, kh is your water's ability to absorb and neutralize acid, AKA alkalinity. So it is basically the main factor in how much your ph can bounce around...
 
So I would want a higher kh than I have now to increase Ph? If so, how do I increase the kh, and what may have caused it to drop in the first place?
 
I've considered adding crushed coral to one of my canisters but I feel like that's just putting a band-aid on it. What might a possible reason be for the kh to go down to begin with? I'd like to come up with a long term solution if possible.
 
Well, if your kh is low from your tap water, it can be more prone to swings. Something as simple as driftwood could be causing ph drop, on top of your cycle. Honestly if you have ammonia in your tank I'd rather have low ph anyway... Ammonia is pretty much 100% ammonium at 6.0 ph (MUCH less toxic in that form).
I'd just start doing 25%+ water changes on that tank daily for a while, wouldn't worry about the ph unless you see signs of stress in the fish. I've seen it argued that ph readings in tanks don't affect fish very much anyway compared to things like TDS...
 
I use a buffer like crushed coral in my CA cichlid tanks because I KNOW my kh is super low out of the tap. People have a hard time grasping the concept that a buffer like crushed coral doesn't necessarily cause big swings when you change your water. It actually does the opposite.

My kh is low. Out of the tap, my water is about 7.2-7.6. If it sits in a tank for a couple days with even a single piece of driftwood, it drops to the lowest reading on the API ph test (6.0 or less). When I do water changes with that with my tap ph being higher, it swings. With a kh buffer, my water stays in the mid 7's all the time. When I do water changes, there are no real swings.

There is a fundamental misunderstanding about the basic ph/kh relationship prevalent in the hobby IME.
 
Which all leads back to needing to know what your kh is. :)

BTW, sorry to be off topic, can you see my avatar picture? I can't...
 
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