[hitmanx]

Started a new 5gallon lowtech heavily planted tank back in march. It's open top and I add tap water for evaporation only... no WC

Day 1 (March 19th)

Flourite Black Sand and Mulm (1L), ADA AquaSoil Malaya (3L), with a big hunk of Malaysian Driftwood

Tap water:
gh 25
kh 16
ph 7.8

I started dosing seachem ferts march 29

Dosed
NPK 1.66ml-7.5ml-1ml + 1/16tsp Equilibrium

gh 14
kh 3
ph 7.4

And a month later, the hardness continues to fall with kh at almost zero!!

April 28

Dosed:
NPK 1.66ml-8ml-1ml + 1/8tsp Equilibrium

gh 16
kh 1
ph 6.8

So by May 5th, the date of my last tests, the gh is rising but kh isnt doing much and ph remains constant...

Dosed:
NPK 1.66ml-8ml-1ml + 1/8tsp Equilibrium

gh 18
kh 2
low ph 6.8

My concern is the low kh... I've read that plants like a mid range kh and it also acts as a buffer for ph swings... I have no fauna yet but I want to add shrimp which need constant ph as far as I've read... is the aquasoil really affecting the kh this much?

As reference, my heavily planted 15 gallon that i started march 2nd with flourite black sand only and a large piece of branch driftwood, and using the same tap water to top off only is very different indeed:

gh 30 (steadily rising)
kh 15
ph 8.2

 

[jrman83]

Have you seen what happens when you do a water change?

 

[greaser84]

The reason your gh is raising is because your topping off with tap water, when the water evaporates it leaves the minerals behind so it will continue to raise.

 

[hitmanx]

Have you seen what happens when you do a water change?

No?

What are you suggesting?

I am trying to adhere to Tom Barr's non-co2 method, so i will only water change if major rescaping is done...

 

[hitmanx]

The reason your gh is raising is because your topping off with tap water, when the water evaporates it leaves the minerals behind so it will continue to raise.

yes, this fact is becoming obvious to me, and is leading to think about using RO water to top off... but the 15 gallon is not the tank i am currently asking about...

until i started dosing equilibrium to the 5 gallon, the gh was actually dropping despite topping off with hard tap water...

 

[Diana]

I you want to adjust the KH you can use baking soda (sodium bicarbonate) or potassium bicarbonate.
I have used baking soda to adjust my tap water for hard water fish (Lake Tanganyika tank) and to counter the KH removing properties of Soil Master Select. The ADA substrates do the same thing (remove carbonates from the water).

1 teaspoon of baking soda added to 30 gallons of water will raise the KH by 2 German degrees of hardness.
1/8 tsp potassium bicarbonate added to 1 gallon of water raised the KH by 6 German degrees of hardness.

Tanks can be stable with no KH showing on the test kit, but the pH in my tanks when the KH is zero or so close to zero is at or below the testing limits of hobby level pH kits. I had to get lab grade tests to show that the pH in some of these tanks was in the upper 5s.

If the KH is maintained at 2-3 degrees then the pH is likely to be in the low but testable range of hobby level pH kits. That is, in the low 6s.

Since other things in the water besides carbonates can play a role in determining the pH it is just fine to target both the KH and pH, and when you find a level that works for you then maintain conditions right there.
With a substrate that removes the carbonates you will probably be adding carbonates often.

Another way to do this is to add coral sand, oyster shell grit or limestone sand to the filter in a bag (I use a nylon stocking) These materials will slowly break down and raise GH, KH and pH.
Monitor it, and you can probably stop adding Equilibrium, too.

 

[hitmanx]

Sorry for the long winded post:

Since I first asked this question, I have since begun RO top off on both of these tanks but i did not try to maintain kh with baking soda in either of them.

The results have been interesting. .. the 5 gallon has since stabilized with gh 25, kh 1, and ph 6.8, with seachem fertz and equilibrium but no baking soda. A thriving RCS colony, 3 amanos and many ramshorn snails have populated the tank since August and I just added 6 cardinia babaulti green... the kh and ph have remained constant all this time and nitrates are almost non existent with around 60% surfsce coverage by frogbit, salvinia natans and watersprite complementary to the mosses and crypts below. ..

My other 15 gallon tank has seen a much different result... the hardness stabilized after switching to RO topoff but the kh began to drop down to 7 in September. .

By the end of September I felt the hardness was still too high so over a period of several weeks I changed 50% of the water for straight RO water with a result of gh 16, kh 4 and ph of 7.5 (down from 8.2), I also added 7 juvenile yellow forktail rainbow fish at this time...

By mid November my ph seemed to fluctuate and my amano shrimp started to get sluggish, turn opaque and by December my kh was less then 2 and I feared my ph was crashing... the amanos started to die and at least 3 CPDs were missing besides the one jumper and one very sick one that I euthanized...

At this time I gave in and added baking soda, enough to increase kh by 1dh at a time... more shrimp died... These fluctuations were no good I determined... kh 5 and ph of 7.8, then you to 8.0 again

This week I added enough baking soda to increase kh by 1/2dh when it fell again to less than 3 and ph fluctuated to 7.5

So as it stands I don't know if this is a simple kh buffering problem and I should or shouldn't be adding buffers to maintain a certain level or whether I have an underlying problem with too much organic acids driving my kh down... maybe my bioload is too high or feeding too much? My nitrates are 80+ppm with no other spikes that I know of and with 7 healthy yellow Forktails and 7 CPDs I don't think the bioload is too high for such a heavily planted tank so I am at a loss... There was even an unknown fish fry seen yesterday so it can't be that bad for the fish if they are breeding

So either I have to make a big water change or add some emersed house plants to suck out the nitrates...

 

[Diana]

If the NO3 is high from fish food, shrimp food and similar organic sources, this is bad. I am not sure it is the NO3 itself, or some other process going on, but you need to do some serious water changes and get rid of the decomposing organic matter in the tank.
I think this is the problem, because the fluctuating KH and pH is also suggestive of a tank with high levels of microorganisms. Some of the microorganisms use the carbon from the carbonates, and the lowering KH allows the pH to fluctuate. (Look up Old Tank Syndrome)

If the NO3 is high from dosing KNO3 I would slow down the dosing, see if the plants can remove it, or perhaps do enough water changes to get it down.

 

[hitmanx]

Diana, thanks for your reply.

Is there a way I can tell what the high No3 is from? Organic or inorganic? The water is crystal clear and it seems like very minimal mulm and grunge can be seen anywhere. I use a eheim 2213 on a 15gallon so I'm over filtered and I use purigen as well. I may have been dosing slightly more nitrogen over that last 6 months but you think this hygrophila angustifolia would soak that up. Currently there are 7 yellow Forktails and 7 CPDs and I only fed them a pinch of NLS 0.5mm pellets per day and the original 12 amano shrimp received 1 hikari mini algae wafer... is this really too much?

Because of the small surface area of this tank (13x13) but larger depth (23in), I cannot use floating plants and maintain healthy stems below as there won't be enough light...

I have heard that nitrate tests can be faulty and I have not calibrated my test kit so can I even believe my results? Are there any other possible explanations for the driving down of the carbonates besides organic acids and wonky redox?

And my second question is about water changes... how can I match my water parameters for changes when the tds is so high in this tank (900ppm+)... If I cut my tap water with 50% RO the parameters would be gh 13, kh 8, ph 7.5, tds 275ppm

Won't this be too much of a shock to my fish? I remember you helped me several months the ago when I decided to make the small 10% changes over time to reduce my hardness without shocking the fish, but can I do that now with the nitrates so high?

 

[Diana]

Do not do such a radical change.

Change the values no more than 10% when you are going softer. Then wait a few days and do this again. Just looking at the TDS:
First water change: 900 - 90 = 810
A few days later: 810 - 81 = 729
A few days later: 729 - 73 = 656
and so on.
When the tank needs a larger water change then do not add so much RO to the mix. Make the mix a bit harder so the end result is not more than 10% drop in the values.

To do a 50% water change:
Tank water TDS = 900
Goal TDS = 810
Remove 50% of the water which removes 450 TDSs (yea, TDS is not actually a unit- I am using it as one 'cause it is easier to think this way)
gotta add back 360 TDSs.
But 50/50 RO + tap is only 275 TDSs, so try 70% tap + 30% RO.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

How to tell where the NO3 is coming from:
Stop dosing. Monitor what happens to the NO3 when the only source you are adding is food for the livestock. If it:
Drops: Plants are using all the nitrogen from the protein in the food, so dose KNO3, but not as much as before.
Stays stable: Do not dose.
Rises: Feed less or do more water changes.