What is function of kh vs gh in keeping ph stable? (ph crashing in my tanks)

[kaytlu]

I'm having a problem that I haven't encountered before... which is probably not too surprising.

I moved to my current location not too awfully long ago, and though the water was a bit different from my last spot, it wasn't overwhelmingly so.

I had lived south of Houston (Rosharon) where the local water co. operated off their own local wells. I am now in La Porte, which has a more sophisticated water set up.

Before, my water had so high a content of dissolved solids it was close to liquid rock, & my tanks had a very stable ph approx 7. Currently, my water is a good bit clearer, but the ph out of the tap is still around 7. I can't remember what my current kh & gh is (no test kit for it right now), but I do remember testing it when I first moved here, & the kh was in the "normal" range, but the gh is quite high... which didn't surprise me at all (hard water scale, constantly!).

Now, my ph has really dropped to around 6 (API kit), and even after a water change when the ph of the new water (~ 7) should add buffering, the tank quickly drops again.

My tanks are heavily planted, but I am starting to lose plants that prefer harder water. I also lost some fish in a weird way... they would look perfectly healthy one day and were dying the next morning!

I'm going to venture out & get some kind of test kit for kh & gh, but I'm still baffeled as to why my ph keeps bottoming out... this is the first time I've ever been faced with this problem.

Prior to this, quite a while ago, I once tried everything I could think of to lower ph in my water, short of jumping up & down on it, with the result that it simply bounced back to it's previous high level. LOTS of buffering! The only thing that worked was simply replacing the local water with RO, and I just didn't want to get into all that set of new problems.

So what's happening in my tanks? What, exactly, provides the buffering properties in the water? Most of my plants still look really good, rotala is good & bushy & pink, ludwiga is a beautiful dark red, micro sword, & hairgrass looks great & I've had to throw away handfuls of the fast growers like water wisteria etc.

I'd like to have fish too, though, & simply won't buy any more until I figure out what's going on. I would truly hate having to tear my tanks & plantings apart & starting over.

[TankGirl]

What are your readings for ammonia, nitrites, and nitrates? What are you using as a substrate? Last water change? Using co2 for your plants?

[troy tucker]

+1 Water changes? how often and how much?

[ptran]

Hope you can give some more information on your tank set up: tank size, filtration, substrate, water change schedule and how much.

[kaytlu]

OK, I went over to the local lfs looking for test kits and the only thing they had (other than Ph & ammonia/nitrate) was an API 5 in 1 test strips thingy.

I know that the strips are none too exact, etc., but it's raining & I didn't want to get into crosstown rush hour traffic.

Anyway, the strips matched pretty well to what my API master test kit did on Ph, Ammonia, nitrite & nitrate plus they gave an indicator that something is definately going on with the GH & KH.

So, what the kits show is:

Ph 6

Ammonia 0

Nitrite 0

Nitrate 0

KH 0 (!)

GH between 120 and 180

The substrate in 2 of my tanks is a mix of an "enriched" substrate from Petsmart (I belive it was called Florascape or similar) and black sand.

The substrate in the other is simply black sand.

I started out using CO2 in one tank, primarily because it came as part of the "kit". I also dosed the tanks about twice a week with Excel.

I stopped using the Excel after it melted my vals, though and stopped using the CO2 when I noticed the ph going down. I used root tabs when planting some of the heavy feeders, and some liquid fert occasionally that came with the kit. (called PlantGro)

The lighting levels on all three tanks are somewhat different. On the lowest lighted on I have a Finnex StingRay (pretty low light) and a
Fluval clamp on (medium light). It's not bright enough to grow dwarf hairgrass & microsword, but It's doing a good job on the Bacopa Moneywort, Wenditi Green cripts, rotala (only pink on the very tips), Anubius petite, and a few odds & ends.

It has a canister filter with bioballs and different levels of foam in it. Mechanical/biological filtration only. This tank has the mixed substrate in it and some root tabs.

Next brightest tank has a Fluval led "full spectrum" strip and Finnex clamp on Planted +... Definately medium high light... Ludwiga, rotala, (both showing a lot of color), moneywort, vals, microsword, dwarf hairgrass and regular hairgrass all doing well, while I throw handfuls of watersprite & rotala away everytime I prune. I ran CO2 on this tank since it was the "kit" tank & is also deeper than the others 18".

The last tank is the 10gal "grow out" tank which I had the hair algae problem with. It has the sand only substrate with some root tabs added. It has internal submersible Fluval filter, also with bioballs and sponge in it.

I thought that I would give it the "bright light" treatment since nothing else I tried seemed to make much of a dent with the algae problem. So, I have 2 Finnex planted plus 30" strips over it that I had intended to use on my 20gal long and 29gal tanks that I have yet to set up.

I have to say that the lights worked like a champ... Not only did the hair algae disappear, but the green algae that grows on the glass also bit the dust! The tank has a lot of plants in it, whether planted or floating around, and under the stimulus of all that light, I suppose they just starved all the algae out.

My water change schedule has been the same for all tanks. Weekly changes of ~ 20%. Lately, though, they've become more like every 2 or three days as I've tried to raise the buffering in the tanks.

I suppose that the plants have simply sucked all the KH out of the water. Carbon hungry!

I read somewhere that slowly adding potassium bicarbonate or sodium bicarbonate to the water would raise KH... I've got the sodium bicarbonate (Baking soda), but would hate to start killing off my plants that are still growing pretty well.

(I suppose I could scurry around and find the exact wattage for each of the light setups, but I don't have it handy & haven't worried too much about the exactness of that)

ALL the tanks, despite the different light & substrate combos show the same low ph, low KH problem.

[TankGirl]

With 0 KH, there's not really a ph buffering capacity, so the ph is going to lower naturally, plus the co2 will bring the ph down even quicker. I'd keep off the co2 until you can get the KH and ph stabilized. If you're not sure about adding baking soda, there are a few alkaline buffers sold for this purpose.

[kaytlu]

I know that 0 KH means no buffering. I'm not using CO2 now.

I think that I will increase the size of water changes to around 40% every 3 days or so until the KH starts to rise again. I suppose that I need to increase the size of my routine water changes once things even out. I guess I'm still used to the way I was maintaining my low tech tanks. They seemed to do best with smaller water changes.

I might also shorten the length of time I have the lights on.

However, I can see that this whole thing could easily happen again if the KH here is that touchy & have decided that some sort of added buffering is indeed necessary. I'll venture over into Pasadena or Webster to a larger lfs to see what's available.

I'm kind of tempted to experiment with the baking soda, but I know that the human body treats it as just salt... I'm afraid that the plants would see it that way also. I might see if I can find some potassium bicarbonate instead. The "bicarbonate" part of that stuff really interests me... I wonder if it would be a carbon supplement to replace Excel?

In the future I would like to return to using CO2 in my tanks, since it makes so much difference in the way my plants grow...

However, other than just satisfying my curiosity in re the bicarbonate, I do kind of hate dosing my tanks with extra chems... The more "stuff" that's added, the more odd interactions that can happen.

[ptran]

Maybe try this home made Rift lake buffer:

http://www.cichlid-forum.com/articles/buffer_recipe.php

[morpheus]

i agree that chasing a specific pH via chemicals is dangerous. starting with hard water and trying to run a soft water tank like you tried in the past can be a real chore. you can create wild swings in your params and usually end up doing more harm than good.

here is an article that gives a pretty good description of the relation for KH and GH to pH:

http://www.fishlore.com/fishforum/ph/113548-understanding-ph-kh-gh-home-aqauriums.html

what is your KH out of the tap? you said you rememebr it being normal, but that is relative to where you live. i was unsure if your zero you mentioned was your tank or tap. if you tap is KH of zero, then no amount of water changes will adjust that figure. i use limestone rocks in my cichlid tanks to buffer the KH slightly, which in turn usually only raises the pH a few tenths. you can also use aragonite sand or crushed coral to buffer and give more surface area contact than a large limestone rock.

i have used the baking soda route before but its like any other chemical, if something is breaking down the calcium carbonate, then the pH will just swing back and forth. i went through my filters and did a good cleaning. ornaments, plants, etc. getting whatever i can out. water changes like other mentioned too.

[Alex1]

What is function of kh vs gh in keeping ph stable? (ph crashing in my tanks)

Sorry

[Alex1]

What is function of kh vs gh in keeping ph stable? (ph crashing in my tanks)

Wrong place

[Alex1]

Ok I think I'm doing this wrong.
So sorry.
I will go to new topic
Sorry Alex1


Black pepper is my salt.

[TankGirl]

Glad you know that already. Lol. Just was trying to help.

[mredman]

Any update?

Generally, the pH will drop about one full point with optimized CO2. There are far more plants that prefer a neutral to slightly acid water. What plants are problematic in your tank?