f1ea

Hi, its me again...

I find it very strange that my 3-4 week old NPT (mineralized soil) is losing hardness like crazy.

I'm using tap water coming from a well with KH 7, GH 12, pH 7.
But my tank water is at KH 4, GH 7 and pH 8.

There's a decent fish load, and i am feeding regularly... 128W + sunlight on a 200 Gal.

I'm concerned because if i am not supposed to do regular water changes, at this rate, over a few months the hardness will drop to 0. Could it?? Also, pH should be decreasing with all the decomposition going on....

Right now its going through its algae phase. Green water, black hair, and 'maybe' blue-green... Its slowly improving, and as i can see, in 2-3 weeks it looks like water will be clear.

Any experiences?? suggestions??
Could i try some Excel to help w/ algae and increase CO2 so that the plants don't steal so much water hardness??

Puzzled...
(Fish are healthy, except for a Rainbow shark that died w/ a swim bladder issue)

Regards, and thanks for all the help!

Diana K

When you put soil under water it will do some odd things before settling down.
If the GH and KH keep dropping you might want to add something to keep them a bit higher. Water changes are a good way to add the minerals back to the water.
I use Seachem Equilibrium to raise the GH, and baking soda to raise the KH for my Lake Tang tank, and a few others. In some of my tanks the substrate keeps removing the KH and dropping the pH below where the fish and plants are happy, so I keep adding more carbonates (baking soda).

You are right that usually a dropping KH is matched by a dropping pH.

What fish are you keeping? Are they soft water fish? Are they OK with the softer water? If not, then I would take steps to keep the water a bit harder, in the correct range for the fish. If your fish are softer water fish then I see 2 options: Let things alone, and see what happens. Things may stabilize in a good range without doing anything. OR take steps to keep the GH and KH up so they do not hit 0 degrees.

f1ea

Hmmm, i could do some water changes and see if hardness keeps dropping...
I also have a Malawi tank: KH 8, GH 13 and pH 8.2; buffered only with some calcareous gravel in the filter media.

This tank is for softer water fish. So i should be happy hardness is lower... i was expecting a lower pH than my other tanks; but i'm more surprised its the hardness dropping and worried it might drop to 0 and destabilize pH...

Fish are:
( 8 ) Angelfish
( 8 ) Black skirt tetra
( 6 ) Serpae tetra
( 6 ) Clown loach
( 3 ) Flame gourami
( 1 ) Pleco
( 1 ) Rainbow shark (RIP)

All of them are young. I will increase the tetra schools in a week or so... and maybe replace the gouramis with 10x swordtails or mollies.

Thanks!

Diana K

Yes, those are all soft water fish. I would not add livebearers to that tank, they prefer harder water.

If the Gouramis are OK in there, they are fine. Good to have some upper level fish with all the low to mid tank fish.

You could test the substrate separately and each component of the tank. Try putting a handful or two of the substrate in a small amount of water and monitoring it for a week or two. See what happens with JUST the substrate. Test the decorative rocks, driftwood and anything else. Test each item separately. Do you have any peat moss either in the filter or the substrate? Peat moss can remove certain minerals, but usually also lowers the pH. Do you have any other products in the filter or tank that might alter the test results?

Another possibility is something going on with the test kit. I have seen some results that seemed quite alarming, but were actually some incompatibility with a test kit. 2 other test kits showed different (acceptable) results, and the fish and plants were fine, suggesting no problems. If you have access to a different brand of test kit, with a different reagent, test the tank and tap with the 'other' tests and see if the results are the same. Are the test kits getting old? Results will not be accurate as the test kits age.

f1ea

Yes the Gouramis are doing very good. They love the tank, and eat lots of algae.. i have nothing to alter the water (no limestone, no peat moss) in the filter media; and haven't added driftwood until i saw what my 'normal' ph was.

The test kit is a Tetra laborett. I use it on my other tanks, and it gives the values i posted above.
I had also tested my tap water a few months ago, and the readings were the same. And the same day tested all the tanks and gave me the results i mentioned above...... the kit 'may' have some error, but at least it is consistent and gives me a good relative view.

Yesterday, i did a large WC (about 40%) and one of the angels got very stressed... hanging at a corner and didnt rush like everyone else to eat... bad sign.

bradac56

Have you tested the water outside of the tank? If it was me I'd put tap water in a bucket, add your dechlorinator of choice test it and then let it set for 24 hours and then test it again and see if it changes the same way your aquarium does. If it does then your water company may be adding something to buffer there water which dissipates over time, that's not unheard of.

It looks like others over at plantedtank.net suspect the same thing.

- Brad

f1ea

Its well water, nothing added to it. I thought it might have changed during the rainy season... but the tap water is giving ther same values as a few months ago.

Dustymac

I think the combination of algae and sunlight has pumped up photosynthesis in your tank, which could lead to temporary elevations in ph. I would try taking a reading in the morning before things get started, and then another test around noon. The accelerated growth could also account for the loss in hardness - all that algae growth is pulling calcium and magnesium from the water. Eventually a nutrient deficiency will stop the algae growth if you don't add more nutrients, and things will settle down. At least that's what I think will happen...

Jim