Ideal Gh And Macro Proportion For Ro Water ?

Neil

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Oct 15, 2018
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I'm using 100% RO water.
2 Years Old Aquasoil substrate
Current water parameters:-

pH - 7.6
GH - 1 dGH
Ca:Mg - 4:1 (Only during Water change day using CaSO4 & MgSO4 on replacement water volume)
KH - ~0
Pressurized CO2 at 4 bps.
Tank water + Sump = 440 Liters.
Tank dimension : 4 Lx1.5 Dx2.5 H ft.
Weekly 25% water change.
Light: LED 220w, 20000 Lumen at 4000K

Weekly Dosing:

Nitrate - 40 ppm
Phosphate - 2 ppm
Potassium - 30-35 ppm
Plantex CSM - 0.1 ppm registered on Iron

Some plants are stunted, tiny leaves and almost 0 growth tops.
Suffering plants are Rotala Rotundifolia, Ammannia Senegalensis and Gracilis and Alternanthera Reineckii Mini (Showing Reds but tiny top leavs but stunted meristem).

While most of the other plants like Limnophila, Ludwigia, Undulutus, Bacopa Glossos and even Tonina and Syngonanthus are all fine and no signs of stunting. Few other plants are even showing red coloration like Ludwigia Glandulosa.

How can i get rid of these tiny leaves and stunted tops ?

Is it something related to GH? because i use almost EI dosing regime so i expect it shouldn't be NPK and micro deficiency..

Is it necessary to add Potassium while making GH mix ? I just do 1:4 Ca (4)and Mg (1) salt mix before adding to RO Water. Nilocg uses 1:3:3 Ratio while Seachem uses 1:4:8 Ratio.

Is it necessary to be K ppm higher than Calcium and Magnesium ppm ?
 
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skija

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Hi

Pressurized CO2 at 4 bps
this gives zero info about CO2 , all the info given by you leads to CO2 issues


Some plants are stunted, tiny leaves
Try increase co2 and flow/circulation in the tank , this is 100% Co2 issue
 

Pauld738

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Feb 24, 2019
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Your pH doesn't match your kh value. If you really are running at 0 kh you should be real close to 7. Than with CO2 injection, even if it's not enough which in a 440 liter tank I'm guessing it's not even close, you should be well under 7.

Are you really adding 40 nitrates?

Fyi

I'm running RO with ~ 1 kh, 7 gh, 5 nitrates

Co2 off: 6.8
Co2 on: 6.0

My rotala rotundifolia has nice leaf growth
My oval ludwigia shows some red coloration.
This with medium light.

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Pauld738

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Feb 24, 2019
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I did make some assumptions based off of OP's post stating he was using almost EI dosing. This made me believe there was weekly water changes. And with that there is probably a good chance that detritus and mulm is being sucked out of the tank on a weekly basis so there probably isn't a huge acid bank driving ph down. OP also stated that gh was at 1. So if he really did have 0kh and 1gh there's not a lot in the water to have such a high ph. This is, of course, provided the OP has accurate test results.

From my own observations on RO water, whenever I stick my ph probe in my holding bucket it reads real close to 7.0 (which makes sense as there isn't much in the water). I have 3 planted (key is planted) tanks now running at no or low kh and they all read right around 7.0 ph (degassed) give or take a tenth or 2 (more take than give). I do have one tank that has a kh of 7 and it runs around 7.6 to 7.8 all the time. Frustratingly no matter what I do. :)
 

Phishless

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This is why a pH controller doesn't work well with 0 dKH water.
With no alkalinity a small bit of anything can drop or raise pH substantially.

I try to @ least keep .5 dKH in my tanks.
Just somewhere under 1 dKH
 

Pauld738

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Feb 24, 2019
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This is why a pH controller doesn't work well with 0 dKH water.
With no alkalinity a small bit of anything can drop or raise pH substantially.
I try to @ least keep .5 dKH in my tanks.
Just somewhere under 1 dKH
So do I! I've even noticed that plants do better (atleast the plants I keep) with a little kh in there. The one tank that I have no kh in is precisely to see why everyone freaks out about ph fluctuations in a low/no kh environment. I have yet to see any issues. But it's a planted tank. I think that changes the game to some degree.

I don't understand your ph controller comment. I may be wrong but the OP didn't say anything about a ph meter. Or what they used to test. I'm guessing you were talking about that? if not, the values I gave were for a tank that has kh. And RO water straight out of tap is going to be 7.0 no matter how you look at it so the ph test really is just for me to see how the probe reacts to RO water. Which in my case is seems to align with what RO water should be.

I would love to see any literature that you might have that discusses a rising ph in the absence of kh/gh. I've looked and just don't see it (aside from the standard "your ph will fluctuate if you don't have any kh"). Not saying that there isn't any. I would truly like to see something that talks about rising ph in the absence of kh/gh with something more than the "it fluctuates" statement and then moves on. :)
 
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Phishless

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PH meter point.
With no alkalinity a pH controller is not very useful since a small amount of any compound will sway the pH drastically.

In a perfect world sealed in some way I guess RO water could be 7.0pH
I haven't seen this happen yet.
Typically RO will fall acidic and not go up.

As soon as any air exposure occurs it will quickly drop into the 5's.
CO2 gets absorbed from surrounding air.
No KH is present to buffer the swing in pH.

KH works in 3 levels reflective of pH.
Bicarbonates, carbonates, and hydroxides.
This would be another talk point altogether.

I guess searching for RO pH results would yield something.
 
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Pauld738

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Interesting stuff. I hadn't thought to search that. I was only doing low kh high pH.

And definitely not my experience. Although it does affirm my position that it is very difficult to have a 7.6 pH with 0Kh and 1 Gh.

Who knows, maybe it really is a measurement error. I know that liquid pH tests are horrible in no kh environments. And probes need correct calibration in combination with the right algorithm. But if that is the case, no one really knows if pH is fluctuating. It's just the test/probe giving false readings.

It's funny, I see chemists and lab people saying RO water is 7ph. Even the pH probe manufacturers talking about how low kh affects measurements say RO water is 7ph. But you go outside that environment and everyone says 5ph and wild fluctuations. Most of the results, first page, from searching RO pH results were from RO manufacturers and they were all 5-6ph.

I guess all my hot air is devoid of co2 [emoji38]

Thanks

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Neil

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Oct 15, 2018
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Okey ... i'm sorry my bad ... there is a mistake related to pH .. KH is 0 .., but the pH is between 6.8-7 i didnt notice my test solution died out..! bought the new ones yesternight..
pH is well around 6.8 DEGASSED ... will do 2 more tests to reach the average .!

and the stunting of Rotalas are gone now ... a couple of tips are still there but ill do trim it off soon.
But i still dont know how the stunting occoured i was doing ~2 ppm (even tried 3 ppm per week ) Phosphates weekly but when i pushed both weekly Phosphates and Potassium to 10 ppm & 60 ppm respectively the stunted rotalas quickly recovered just in a couple of days. Rotalas, Ludwigiasare growing like weed now, but what makes me sad is AR Mini and Ammannia Senegalensis and Gracilis are literally going even more curly worse than noodles growth rate is just undestinguishable. Even though i did pushed my GH to 8 with Ca 3 : Mg 1 ratio so there is no question of Calcium or potassium deficiency..!
 

Neil

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Oct 15, 2018
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India
Will you call it high light as im using all LEDs ? though not any professional LEDs .... i built my leds using Cree LED chips based on their output spectrum... Its a non-RGB though.

I've read high lights uptake more nutrients and shows deficiencies even quicker !
I dont know if it falls under High light category as i dont have a par meter and i have a fairly deeper tank as compared to others.. My Rotala Macrandras and Hra are not red but sort of ORANGEish..! but Ludwigia Glandulosa is like reddish Maroon and Ludwigia Ovalis is Reddish Orange!
 

Pauld738

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Sorry, I don't have experience with AR Mini, Ammannia Senegalensis and Gracilis.

I would try bumping up the kh just a smidge. See what happens. Other than that maybe post some pics over on plantedtank.net (have you already posted over there?). There are some people on there that are very good at pinpointing what deficiencies are going on based on what the plants look like. Or atleast good at pointing you in the right direction.