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Water as hard as liquid granite; ferts plants and any other advise

2093 Views 19 Replies 5 Participants Last post by  scollinguk
Hi Everyone,

Can i say firstly that although this is my first post I have been viewing these boards for months now and they have always been able to solve my questions just by searching, you are all such a knowledgable bunch!

This time though I am looking for some more specific advise about how to move my tank forward:

I have a Fluval Venezia 190 corner unit (it passed the wife consideration factor more then the others) which I have have customised. I added a double power compact which brought the total light power to 120w, started with DIY co2 and now have upgraded to presurised bottles running on a pH controller, added fans to cool the water, and an extra filter in the form of a Eheim Classic 2217.

I have Seachem Flourite as my substrate and a couple of quartz rocks as decoration. I have been dosing 5ml of Flourish and 30ml of Flourish Potassium each week after waterchange.

I started with the following plants:

Echinodorus Tennullus
Eleocharis Acicularis
Eleocharis Vivapara
Hygrophila Rosanervis
Myriophyllum Mattogrosense
Hemianthus Callitrichoides
Vallisneria Spiralis

I found that the Hygrophila went berserk and grew like there was no tomorrow and was all over the tank and had to be cut back every couple weeks or it would take over the tank. During this time both eleocharis and the myriophyllum slowly died back to nothing and the hemianthus, echinodorus and vallisneria not really doing anything although the echinodorus did propagate four new plants over about 8 months but turned a brown colour.

Six of seven weeks ago removed the hygrophila and found that within a few days the echinodorus started sprouting new growth and the leaves seemed to be getting rid of their brown colour and turning a nice green beginning in the middle of the leaves and stretching outwards. The Vallisneria started to show growth and now is propagating very well, doubling in amount of plants in about 6 weeks! The hemianthus seems to have literally disappeared (although I think my tiger barbs have slowly ripped it up).

About a month ago I also added a mat of Vesicularis Dubyana, some echinodorus latifolious and two aponogeton madascariensis.

The Vesicularis has been quite strange and had new growth after about a week but now, three weeks later, has started to turn brown. The echinodorus latifolious again is strange, half of them have turned brown and started to shed leaves and half are a lovely green colour and i can see some new leaves and sprouts coming from the base of the plants. I am planning on removing the brown leaves shortly (just waiting for long scissors and tweezers to be delivered). One of the Aponogeton has been doing very well and seems to have a new leaf developing every other day, the other one i found had been uprooted and now it is back in the substrate seems to beginning to get along.

My current water readings:

NH3 0ppm
NO2 0ppm
NO3 10ppm
PO4 2.5ppm
Fe 0.1ppm
KH 28d
GH 30d
pH 7.0-7.1 (aged tap water is ph 8.2)

I know the first thing you are going to ask is if the KH and GH is correct, and yes it is. Our tap water comes out at 17dGH and in both my tanks this increases (although my cichlid tank has both about the 23d level).

Now that i hope i have given enough information about what i have done I can start asking for some advise.

I have ordered some macro ferts so that i can increase my NO3 to be inline with PO4 using the 1/10 PO4 to NO3 ratio and increase the Fe to stay around 0.5ppm (its costing me a arm and a leg to try to do this using Flourish) are doing both these things good advise to do?

Would you advise anything else to do with ferts or thing what my limiting factor would be in this circumstance?

I would like to get some to use as a lawn but nothing seems to be comfortable enough in my tank to do this, can you give any advise on a good plant that could be used as a lawn for me?

What do you think of my current plants, anything you would remove if it was your tank (I am a bit sick of brown leaves) and what would you replace it with?

Sorry for the long long post but hopefully you have the full picture!!


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Very hard water indeed. You could create a unique Hygro-only tank perhaps.

Did you figure out why the KH goes from 17 to 28 degrees? Is someone adding baking soda to your tanks?

I think if your measured values are correct, they are unsuitable for most plants. 17 dKH might work for hardy plants, but almost doubling that... I don't know.
I havent worked out why the KH is so high, I am going to test my Cichlid tank and tap water again just to make sure its not the test or anything silly.

If this doesnt work out then i suppose my only other choice would be to begin using RO water as well as tap water when I do a water change and try to keep it stable.

What would be a realistic value to try and keep it at bearing in mind the lower the KH the more RO I would need to use and the additional cost involved?

I think with a KH around 10 you can keep a wide variety of plants very well, including Swords and Crypts and many others.

You can go as high as 15 and grow hardy plants like Hygros, Vallisnerias, etc.

I am very surprised that Apono madagascariensis is doing well in your situation. I have to try that one day!
SO just checked my cichlid tank and my tap water. They came out as 10dKH and 13dKH.

I think I will do a large water change tomorrow and then test daily for KH to see if it raises.

What would raise my KH in the tank?
A 50% water change later and my KH is down to 22d.

Better but still more to go, really having to think about RO water now.

Whats the normal cost of RO water?

My initial thoughts are to get 100l of RO water and do a water change with that which in theory should bring it down to 11d and then add in a good amount of ferts.

Which does bring me onto another question, I got some macro ferts off ebay and wanted to test their strength.

I bought some spring water from Tesco and tested it for PO4 which came out as zero (thank god, otherwise i just bought water for no reason) then added 2 grams to 100ml. I then did the test again and still got zero PO4.

Would I need to leave it for a certain period of time in order to get a reading for PO4 due to it needed to breakdown or have I just bought some poor quality KH2PO4?

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Hi Happi,

Thanks for that, its really interesting.

That thread points towards plants being able to grow in any water hardness as long as there are the necessary ferts being applied (and enough light and co2).

I am thinking that this is true to a degree but think that there will come a point that the water is too hard especially as the person that posted as having really hard water with pics of his very green tank had 200mg/l which according to wikipedia is 11dKH and my tap water is 13d and the tank seems to be raising it (currently to 22d).

I might post the link to my thread on that thread to see if they can cast an eye and give their opinion too.

My tap water is about the same as yours (25dkH, 35dgH, 8.4 pH). Unless you're trying to grow something like Toninas or Eriocaulons that need very soft water, I've found that most other species will adapt just fine.

Brilliant, its nice to hear that my hard water isn't going to give me the issues that I thought it was going to.

Today I got my new ferts and did the whole range of tests again:

Fe - Less then 0.1ppm
NO3 - about 8ppm
PO4 - 2.0ppm
KH - 23d
GH - 30d

I dosed 5g of my trace mix would would bring my Fe up to 0.5ppm and 1/2 teaspoon K2SO4.

I also ordered some KNO3 so that I can bring the NO3 up.

Is there any other advise that I should be following at the moment to try and get the plants that I have at the moment to come back to being green instead of brown?

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my plants did not do well until the co2 was diffused properly in the tank, being a 50g tank co2 was hard to get in all the places in the tank, so extra flow was also required. drop checker is not very accurate in big tanks IMO and even if you see that its green, you still might not have enough co2 in your tank.

i came to learn that co2 is most important overall other things. you can feed all the nutrients and give all the high lights and your plants will simply die, melt or fall off. again this is an co2 issue and i don't think water hardness is the main problem here. i have grown many kind of plants but they only failed in my bigger tank, however they did fine in small tank, i guess co2 was not getting to the plants correctly.

if you really worried about your water, then please try the following and you will know for sure:

buy a small half a gallon container (see through contain works fine), you can buy it from walmart for $1 or less. add some substrate in it and add allot of nutrients in it, you can overdose it as many times as you like since you wont be adding any fish into it anyway. if you will be planting rooted plants then add some root tabs also. put it under good light and leave the co2 running in it, again you don't have to worry about overdose. you don't need to add filter or anything else in it. just make sure you have the good light over the container and feed them all of the nutrients and while co2 running on it. if your plants grow in that container then water is not an issue. its more of co2 issue rather than anything else. fertilizer will only give benefits if co2 is there, otherwise daily feeding of fertilizer is waste unless you are running high light and high co2.

try this and post the results and pictures. can you please give more detail about your setup about light, co2, fertilizer routine etc. how you know how much co2 is in the tank and are you having any algae?

please post a picture of your fish tank.
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Interesting, I use a pH controller to control my pressurised co2, this keeps the tank between 7.0 and 7.1, I also have a pH monitor that is like a temperature monitor which I have just used to test different areas of the tank, it ranges from 7.0 by the probe attached to my pH controller to 7.1 at the place in my tank with the worst flow and 7.07 in the middle of the rocks in the pictures. Flow is generally good in the tank due to having two canister filters on the same tank.

Algae only occurs the day after I dose 10ml of Flourish but then that is it, normally I only dose 5ml at a time.

As for my dosing regime; I have been lazy with it previously and just dosed 5ml of Flourish and 30ml of Flourish Potassium each week.

I am now testing for Fe, PO4, NO3, and KH every three days and will be dosing Macros of KNO3, KH2PO4 and K2SO4 and a Trace Mix to bring them to 20ppm NO3, 2.0ppm PO4, 20ppm K, 0.5ppm Fe.

I am still waiting for KNO3 to be delivered but have the others and began my dosing yesterday.

I have the standard lighting in the tank (2 x 24w T5's) and two additional 36w power compact bulbs, this giving me my total of 120w.

I think your idea is a good one, funnily enough I have a 15 litre clearseal tank just lying in my office at the moment so I am going to try with my improved dosing and see if it helps my plants if that still doesn't work I will give it a go.
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SO just checked my cichlid tank and my tank water. They came out as 10dKH and 13dKH.....
Then the next day
A 50% water change later and my KH is down to 22d.
That's confusing to me. Either you mistyped or are testing something wrong? I think you meant to say up to 22dkh? I think someone mentioned it already but mixing RO or distiled water into your mix will bring kh down, although as also mentioned this may be no concern.:icon_neut On a decorating note, if you're using seaview on your background, squeegee some more :wink: Your val. should be growing and reproducing much faster, this is interesting. Off to read happi's link.
Yes Ckarr , you are correct, its a mistype the second word 'tank' should have been 'tap'.

I have edited and corrected it now so it makes sence.

The Val is growing at a reasonable rate and reproducing a lot, more then I will want in the long run. Its more the Echinodorus Tennullus that I would like to see doing a bit more!

Although saying that, it seems to be getting greener again, hopefully this is due to starting my improved fert dosing.

Anyway, I am now off to do all my tests again, I'll post the results afterwards.

Cheers everyone!
Right so my results this time:

PO4 - 2.0ppm
Fe - 0.1ppm
NO3 - 8ppm
KH - 25d

I have dosed 4g of my trace to bring Fe back to 0.5ppm and also 1/2 teaspoon K2SO4.

Obviously this shows that something is raising my KH as its gone from 22d to 25d in 4 days.

Can anyone advise what raises KH?
Has someone mentioned baking soda or some sort of buffer? Other than that something breaking down in the tank like coral or aragonite, I doubt that's it and they wouldn't raise the kh that fast. Using ro or distilled would help bring this down as mentioned and also lower that PO4, which is probably coming from the tap water. Getting that down may help control the algae and save you on dosing other items. I can't remember if the light cycle has been mentioned either?
Hi Ckarr,

When you say the light cycle do you mean how long the lights are on etc etc, if not then I probably havent had the light cycle explained to me!

The good news is that I seem to be having some success and the plants are really beginning to turn green again!!!

This is without using any RO water or doing anything to lower the KH. I think I am going to permanantly have to keep an eye on the KH. I think I will see how often I need to do water changes to keep the KH as around the 18d mark but I think that the main reason for having green plants is finally sorting out my dosing regime.

I will keep this updated as things move forward and post some more pictures once we have a good amount of greenery!

Lets keep fingers crossed that the plants keep moving forward and I end up with a beautiful planted tank!
Yeah, sorry about that, how long do you run the lights? It seems different for everyone but 10-12 hours is pushing it and may be a cause of excessive algae growth. Glad to hear things are looking up. Don't foget to update the pics in a couple of weeks.
Sorry for not doing any updates for a while!

My tank cycle is 11 hours, from 9am to 10pm.

Well things seem to be going very well! I have pretty much been keeping the tank at 2.0ppm PO4, 20ppm NO3, and 0.5ppm Fe. Algae has calmed down and now I only need to give the glass a clean about every 10 days. The echinodorus latifolious is even propagating now!

Interesting the KH has stopped raising after water changes and is slowly dropping with them now, currently it is still sat at 22d but I am going to do a water change with some RO to bring it down a bit quicker and as my tap water is 13d I am hoping it will settle there. I still can explain what was increasing it but what ever it was I can only hope it was a limited supply which has now run out.

I have posted new pics below and as you can see we have a lot more green and a lot of growing going on.

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