Help understanding my numbers - The Planted Tank Forum
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post #1 of 6 (permalink) Old 01-12-2013, 12:03 AM Thread Starter
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Location: Georgia, USA
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Help understanding my numbers

I am looking for some help in handling my situation. I enjoy reading/learning about my hobby, so I'm quite happy with some links but I am having trouble sorting through the amount of information (and misinformation!) to arrive at where I think I need to be.

My tank: 65 gal, 60 lbs flourite sand substrate, EI dosing dry ferts(see below), CO2 via Excel (may upgrade to pressurized in the future)

+/- 3/4 tsp KN03 3x a week
+/- tsp KH2P04 3x a week
+/- tsp K2S04 3x a week
+/- tsp (20ml) Trace Elements 3x a week
(honestly, I tend to dose a tad less as my tank is on the low end of the 60-80 gallon range)

So my problem: I have very soft water, of the readings I've done in the last few weeks roughly:
PH: ~6.6
KH: ~1
GH: ~2

So I've recently started doing EI and was planning on weekly 50% water changes, but I've noticed a pattern with my water changes that I need to solve in a more efficient manner. Doing a ~40% water change took my tank from:
PH: 7.2
KH: 8
GH: 15


PH: 7.2
KH: 4
GH: 15

I have Seachem carbonite that I dosed 98ml into my 65gallon (a 50 gallon dose) to raise the KH back to avoid a low KH leaving me open to PH swings. This will usually bring the KH back up, but usually brings the PH along with it (and it shouldn't I thought?) Yesterday I got:

PH: 8.0
KH: 10
GH: 15

And today:

PH: 7.7
KH: 8
GH: 18.75

I have been reading a ton since I got back into keeping a tank - and I agree with the idea of not fighting my natural water more then I have to. I would like to let the fish to get used to the lower PH of my water (which isn't that low anyway), and only increase the KH enough to not worry about PH swings. (It is my understanding that the plants can tolerate the softer water as well as they will get their ferts mostly from the dry ferts I am dosing)

So what I think I need, is a better understanding of my soft water, and ways to deal with it. Things I'd like to understand better/change:
1) How much KH/GH do I need to keep the water safe for plants/fish and not worry about PH swings?
2) I'd like to find a cheaper way then Seachem carbonite as I'm using 1/3 of a $12 bottle every water change.

Thanks to everyone in advance. I appreciate many of you sharing your experiences and ideas !
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post #2 of 6 (permalink) Old 01-12-2013, 06:56 AM
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If you are keeping soft water fish....
Your GH and KH are best at not much higher than about 5 German degrees of hardness. Some of these fish appreciate the organic acids that peat moss adds to the water.

If you are keeping hard water fish....
The GH and KH are best well over 10 degrees, and many of these fish are best when they are in water that tests about 20 degrees each GH and KH.

Research the fish you want to keep and set the GH and KH to suit their needs. Most aquarium plants are fine in either sorts of water.

To raise the GH, add Seachem Equilibrium. This adds calcium and magnesium in a good ratio. It also adds potassium. Maybe not enough to count as plant fertilizer if you only need to add a low dose of Equilibrium.

To raise the KH add baking soda. Carbonates are a buffer that will raise the pH.

To lower these values blend tap water with RO water. It used to be said that you needed a minimum KH of 3 German degrees of hardness to keep the pH stable. This is a good target number. The nitrifying bacteria use the carbon from carbonates, and if the level were much lower the tank could crash.
On the other hand a lot of people have stable tanks with KH of about 1 degree. Quite a few of my tanks have a substrate that removes the KH from the water. But I am only doing DIY CO2. Not enough to really alter the pH all that much.

Fish do not care about the pH nearly as much as people used to think.
The daily pH cycle created by the plants does not bother the fish at all.

Changing mineral levels does bother the fish, and can kill them. When you have set up the tank the way you want, prepare the water for water changes ahead of time so the mineral levels match.
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post #3 of 6 (permalink) Old 01-12-2013, 08:21 AM
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What lighting level do you have? It seems like you're dosing for a high light/tech tank which may not be necessary especially without pressurized CO2.

I can't tell from your OP, what are your parameters of the actual water change water before you do anything to it?
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post #4 of 6 (permalink) Old 01-12-2013, 01:48 PM Thread Starter
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Thanks Diana. In my reading I have been finding what you said - that fish are not as concerned about the PH as many people think. Many fish seem tolerate to a wide range of PH as long as they are adjusted to it. What people seem to do is get a fish that prefers a high PH fish and a fish that prefers a low PH without knowing it and have trouble keeping them together. What wasn't clear from my reading was how much KH I needed to prevent the dreaded PH crashes I read about. If you think I can safely keep it as low as 3 that would make it easier - I have been shooting for 8-10KH as a safe number from what I had been reading.

I have yoyo loaches, neon tetras, and mollies. The mollies may end up at a friends tank soon as I was unaware of their brackish preference/preference for harder water - and I plan to keep softer water more in line with my tap water. The neon's like very soft water, and the yoyo's will tolerate up to a medium but prefer a bit softer as well. So in terms of a target, I am shooting for soft water that I can easily dose my tap water into when I do a water change. I don't mind adding a chemical to raise the dh/kh when I do a water change, what I don't like is the idea of every water change cause these sort of ups/down while I restabalize it if I plan to water change weekly - that seems unfair to the fish. The better solution seems to be to setup a tank with water conditions close to my tap water (or that I can RELIABLY set it to) and find fish that like that.

From what I understand, using RO water is to remove GH/KH so as not to make changing the PH difficult from the buffering. Given my water is practically nonexistent in that regard, I don't see RO being a large benefit for me?

Sorry, it was a bit of a wall of text Tap water numbers:
PH: ~6.6
KH: ~1
GH: ~2

Lighting is DIY 4x 13w 6700k CFL w/ metal reflector (Old T8 hood converted to 4xCFL). I am adding excel daily as my CO2 source while I decided if I want to go pressurized CO2. That is why I am doing a tad less then the generic EI dose as my 65 tank falls in the low end of the 60-80 tank range and my CO2 is not a pressurized system.

I hope this makes sense. I was just trying to avoid adding my low ph/low hardness water which brings down the tank, then i dose chemicals to raise the hardness which seems to raise the ph more then I want, and then after a few days it settles back down to about 7.2 where my PH seems to hang out normally. Because my water water is so soft I will target soft water and reduce the amount of fighting I have to do with my water What I wanted was to understand KH better - and how much I needed to prevent the dreaded PH swings - and a better way to add it to the tank. Using Seachem Carbonite seems to raise my PH temporarily as well - but that may be because I was targeting too high of a KH (8-10) before. I will have to slowly adjust my tank down and see how it goes.
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post #5 of 6 (permalink) Old 01-12-2013, 09:02 PM
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My tap water parameters aren't too far off from yours. I think shooting for an 8-10 KH is a little too much.

I still think you're dosing too much too often. That dosing schedule is for a high tech/light tank.
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post #6 of 6 (permalink) Old 01-13-2013, 12:41 PM Thread Starter
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Yeah the 8-10 KH was what the LFS was recommending as a generic number - I believe I will target around 5 if that will be enough to keep my PH stable.

While I recognize excel isn't as good as pressurized CO2, I thought my light would be sufficient. Based on the CFL research Hoppy did here: Lighting an Aquarium with PAR instead of Watts
take a look at this chart:

he shows around 35 PAR at 24" for a 15 watt CFL mounted vertically. Now mine are horizontal and if you look here:
PAR Data-Spiral Power Saver Bulbs, lighting question
you can see that horizontal is less efficient - maybe by as much as 50%. So if I am only getting 35/2 or 17 PAR/light x4 I am 68PAR - and anything over 50 Hoppy classifies as high and I need to worry about CO2/ferts.

Don't get me wrong, I am totally new at planted tanks/lights/ferts all my experience was just fish and plastic plants before, so if you can help me understand please do. I just need to be able to understand to accept it
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