View Full Version : Low PH

01-13-2005, 04:38 PM
Ok, I've been researching on the site and it appears most people have issue with increased PH levels. I however have the opposite, my PH is at 5.0.
I just did a 50% water change two days ago and checked the PH right after the change and it was at 6.0 (my tap water is 7.0). When I do a water change I usually put 1 tablespoon of aquarium salt per 10 gals of water changed. I checked the PH last night and it was again at 5.0. Is it possible the aquarium salt is lowering the PH? I plan to test this theory but thought in the meantime I would post my question the fish are active and eating like the little monsters that they are.
Set up as follows:
I have a 125 with sand substrate, beneath that I have egg crate filled with gravel (ported from a 40 gal to jumpstart the tank). I have all plastic plants & décor. I have two Pro-Heat II 350 watt heaters, two Rena XP3 canister filters with Floss, bio-mix, & foam pad. I also had a nice piece of drift wood in the tank as well but have recently removed it thinking this could have been the source.

01-13-2005, 09:39 PM
I have a similar problem with my PH being very low. Like 5.2 to 5.5 and I cant seem to do anything to raise it. I can change half the water and in a few days it stabilizes around 5.x again. I have SA cichlids and silver dollars so I dont know what they think of this :) I have lots of driftwood which might be doing this.

PS. I live in Toronto Canada. Dont know where you are but if its around here...then maybe its the water or something.

01-13-2005, 09:46 PM
driftwood lowers pH. this is prolly the source of the problems? i have never heard of aquarium salt lowering pH.

01-13-2005, 09:48 PM
Driftwood does lower pH, how ever I would ask both of you how your fish appear to be doing, and how long they have lived under this pH?

if they have lived under it for a long time and are fine I would let it be.

01-13-2005, 09:52 PM
Well my fish have been in this low PH for around 4-5 years. My Pleco has been in there for around 8 years. Its a 100 gallon tank with 1 Albino oscar around 11" long, 10 silver dollars around 5" long, pair of cons around 5" long and the pleco around 14" long. I will be upgrading to a new tank in about a year. A 220 most likely.

As for filteration, I used to run two AC 500 and two pro-60 kits each powered by a powerhead. Now I run an Eheim 2260 canister filter.

01-13-2005, 10:58 PM
Well my fish have been in there since around June 2004. As an experiement I put the drift wood in a 5 gallon bucket filled with tap water (7.0 PH). The PH has remained at 7.0 while the tank went to 5.0. I find it difficult to believe that the plastic plants and decor would have anything to do with the botttoming of the PH. The tanks has been fine in the past. Like I said everyone seems happy, their eating and swimming belly down. Oh yea, I'm in Seattle. I wonder if someone croaked in the tank. Would a decomposing body cause a PH imbalance?

01-14-2005, 07:39 AM
Try getting some crushed coral and putting it in your filter (in a nylon stocking or media bag of your choice. Gradually add more as needed (over weeks). It will gently raise your ph and stabilize your water. I have heard of excess waste causing instability but I've never experienced it. I'd give the tank a good vacuum and try the crushed coral. I've found that to be the safest way to alter your water without shocking your fish.

z rock
01-14-2005, 09:21 AM
If you are keeping South American fish low Ph is probably not much of a problem.

Kh carbonate is the only thing that buffers water to maintain Ph.

1-2 teaspoons of baking soda (sodium-bicarbonate) into freshwater would probably hold it at 7ph but you might try the coral and see how that does first.

Your water must have no buffering capacity whatsoever.

Bacteria "eat" carbonate in the process of performing the nitrofication cycle.

Salt has no effect on hardness Ph or Kh.

Running two canister filters would contribute to a Ph drop. Massive amounts of bacteria would reside in there and in your substrate that consume carbonate and produce waste by-products (acids).

Clean filters carefully by swishing out in tank water.

That eggcrate covering the gravel may be source of bacteria buildup.

There are two types of bacteria, one grows on fish waste and other dead bacteria and multiplies much faster that the good bacteria. This nasty brown bacteria must be removed or it smothers out the good stuff that grows on tank surfaces. All these bacteria consume carbonate. Carbon the source of life.

01-14-2005, 10:21 AM
Thanks Z Rock. I did another water change last night and pulled all my plastic plants and plastic decor out. The water was a 6.75 last night and again this morning. After I pulled all the plants and decors I did some pretty deep cleaning in the substrate. If it goes back up it has to be the filters, that's all that's left. I haven't change the floss in them for quite a while. All my other levels are spot on except this blasted PH.

z rock
01-14-2005, 03:20 PM
Might want to just clean one filter then hit the other one in two three days. If you clean a canister too well then you'll have no bacterial filtration.

Heterotropic bacteria grow on and break down organic material. These would be the brown nasty stuff you see when you rinse a pad out in the water.Not necessarily a bad thing. These reproduce at a phenomenal rate.Every 24 hrs. They will smother out the nitrobacter

The nitrosomas and nitrobacter that convert ammonia take about 3 days to reproduce. These grow on the surfaces of the aquarium and are the slimy clear stuff you feel on the glass or may blow out when you turn your canister on and off. They would be clear or white hair looking stuff.

Sorry for the information dump. I like to review myself now and then.:lol:

Oh yea! All these bacteria will function between 6.5 - 8.5 Ph but optimum is about 7.5 - 8.0 Bacteria don't like fluctuating Ph values anymore than fish do.

01-14-2005, 03:28 PM
Thanks again Z Rock. I'm worried now that I pulled all the plant and decor out. I might have shot myself in the foot. I definatley will only do one canister at a time. Is there anything I can do to promote the nitrosomos and nitrobacter growth?

01-14-2005, 08:15 PM
You should be fie with decor out, no foot shooting there. As always Z is spot on. To promote healthy bacteria I would service the canister at least once a month and never over service it. You want a consistant flow rate to bring exygen to the good bacteria. Also weekly water changes with a gravel vac of half the substate every other week will help lower nitrates and keep pH up some. As Z said the nitrogen cycles while absolutely necessary lowers pH.

I find it interesting that volume wise my tank has a heavy bioload than yours and a higher filtration rate and yet maintains pH. The water I use is fairly hard and buffered additionally with crushed coral. I think perhaps your water is rather soft.... is there any chance you are on softened water? If that is the case then it would be a good idea to follow Z's instruction of the baking soda as a buffer. Carbonate buffers against pH drop by nutralizing the acid from teh nitrogen cycle.

Sorry for teh book, hope it clears up more for you.

z rock
01-14-2005, 08:22 PM
Here's a link to Seachem:

The Seagems has articles on bio-filtration, ammonia, ect. bunch of interesting reading.

The nitrosoma's etc. basically need oxygen/water circulation. I'm running 2 emperor 400's with the bio-wheel things on a 125g. When I clean the front glass with a scraper that white hairy stuff comes off like crazy.

Marineland has a bunch of good articles on filtration also.


z rock
01-14-2005, 08:34 PM
Ah yes! Here we go.


This paragraph may be a particulare interest:

The biological filtration media in canister filters suffer from this oxygen dilemma too. When clean, the media receives a lot of oxygen via the aquarium water. But as the canister clogs and the flow rate is reduced, less oxygen is brought to the nitrifying bacteria while at the same time more organics are trapped in the canister consuming oxygen. This double negative significantly reduces the effective surface area of the biofilter media.

01-15-2005, 12:29 AM
Awesome, you guys rock. Thanks for the tremendous amount of information. I performed a pretty thorough cleaning of the substrate and it's still holding @ 6.75. I'll clean the one canister tomorrow and see what happens. Normally it was holding at 7.2.

Aside from my PH issue the rest of the water parameters are as follows:
NH3/NH4 = 0mg/l
NO2 = <0.3mg/l
GH = 3°dh

01-15-2005, 12:49 AM
hey sky...
keep up the gravel vac
But i'd also add a little crushed coral...it can't hurt.

01-15-2005, 07:43 PM
Originally posted by SkyDiver85G


As already noted, your water has virtually no buffering capacity. Now test your tap. If similar, you'll need dissolved carbonates (e.g., the result of adding limestone, aformentioned coral). Assuming the test is correct, any KH reading below ~5.0 DH makes the water suspect for pH swings. (I've read claims of stable pH with KH values of ~ 2 DH--including at least one on this board a while back--but I'm not sure how those aquarists manage it.)

01-16-2005, 04:12 AM
Looks like the other's have you helped out pretty well, Tom has a very good idea on testing your tap. Deffinetly get some form of slow disolving calcium carbonate based rock in there, coral, limestone, something. You don't need much as too much will bring your pH up as well if your hardness is that low. I would say go teh baking soda route but for teh possibility of making teh chemistry adjust too quickly.

01-21-2005, 11:09 AM
Methuse works for me, I'll take note of his behavior on his next review <G>. LOL The water tests at 7.2 from the tap. I just checked the PH and once again it's at 5.0. The fish seem happy, I'm heading to the LFS to get some crushed coral to put in the canisters. I'll start out with about 2 lbs and see what that does. Thanks Agez for sticking up for me!

01-24-2005, 12:18 PM
One real quick question, actually after the fact. I bought 10lbs of crushed coral. I rinsed and put in 5 lbs. My PH is at 7.5 and holding. Will it have the same affect if I bury it under the sand substrate I have? I really like the look of the sand and I'd like to have it underneath the sand if possible. I didn't want to put it in the canisters and I thought it would look tacky if I just had it in bags in the back portionof the tank.

01-24-2005, 12:58 PM
You can put it under the sand, not sure the effectiveness,sand may reduce the water flow around it. I'd try it and just keep up with the good minitoring like you have been.

This would probably be better:
If you have available space in one of the cannisters I'd put some there and some under the sand, the crushed coral will continue to buffer and act as media in the cannister. Just bag it in a nylon end or something if you put it in a cannister.

01-24-2005, 01:02 PM
Cool, thanks!

z rock
01-24-2005, 04:02 PM
The cichlids will probably dig around in the substrate so much nothing will stay put for long.

01-24-2005, 04:05 PM
So Z, I take it the coral does loos it's buffering abilities if it's buired in the sand?

01-24-2005, 04:12 PM
The concern would be that it wouldn't be in contact with as much water, which could slow the disalution... You can always try it and see, if your hardness dips then some in a cannister would be a solution.

01-24-2005, 04:14 PM
Alrighty than, I'll probably have to remove some of my bio-mix and replace that with the coral. Thanks Z, have a great day.

z rock
01-24-2005, 10:41 PM
Using the coral as a substrate probably doesn't do a whole lot without water circulating through it. Only whats in contact with the water would dissolve. At the Ph yours is dropping to you will probably need all the help you can get.

Here's a quote from Marineland:


Alkalinity can be replenished by adding buffers to the water. The most common buffer is sodium bicarbonate (baking soda). For marine aquariums, calcium carbonate is widely used to add both calcium and alkalinity to the sea water. Care must be taken when adding some buffers as they can cause the pH to increase very quickly, shocking the fish. The best way to replace alkalinity is by regular water changes.
End quote:

I did run some of that Carib-sea cichlid mix with an undergravel filter in some fry tanks once and it seemed to hold well, but that was a massive amount of substrate surface area to 20-30 gals. of water.

01-25-2005, 12:49 AM
Right now I just spread the 5lbs of crushed coral on the bottom, I have a power head and two XP3 cannisters so I have plenty of flow. I guess I'll replace some of the bio-mix in the cannisters with the coral. Thanks again Z.

01-30-2005, 10:50 PM
Just as a follow-up. I decided to leave the crushed coral spread across the bottom of the tank. PH is still holding at 7.5 and all my little fishies are swimming with smiles on their face.

Methuse, can you check to see if bird excrement is a natural buffer? <G>