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Just a quick CO2/plant holding tank question.

ForestDave

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12 Nov 2020
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Hi.
Total newbie here, so apologies in advance!
I've been doing the research but couldn't see much about holding tanks.

I've been gathering plants in a 200L holding tank for about 3 weeks now and should hopefully be doing a final scape and setting up the tank at the weekend. There's about 35 plants in there and I've been keeping the light low,(2x 39w T5s for 4.5hrs) and adding 50% Ei fertz and doing a water change every 3 days. Filter is a FX6 with a full width spray bar.
I've discovered in the past 3 weeks that my Ebay cheapo regulator is pretty uncontrollable and am replacing it with a CO2 Art dual stage one which I should hopefully receive tomorrow. The crap regulator didn't stop me trying to get the CO2 drop checker to go lime green over a 2 hours period ready for the lights on. I'm temporarilly using a in tank diffuser and found that even if I let it take 3 hours to turn lime green by the end of the 4.5hr light cycle it had gone more yellow. This happened yesterday and the plants obviously were not impressed and shed a load of decaying leaf matter. My KH is 4 and GH is 6 according to the NT lab test kit and there's no substrate. PH goes from 7 to at least 6 when the CO2 is on, (my test kit doesn't measure below 6).

I'm pondering whether
-on a short 4.5hr low light, low fert growing cycle, the plants maybe grow too fast with lots of CO2 and start dying after they run out of fertz?
-There is probably a degree of leaf die off from emersed leaves being replaced with submersed leaves.
-I probably should have done daily water changes?
-I put too much CO2 in and turned the water too acidic?

Any tips on what's going on here please?
Thanks!!
 

SRP3006

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Are the plants new? As in just bought and have been grown emersed?
As for the co2 you can't put too much co2 in the water, 30ppm is recommended in water to keep fish 'safe' however emersed they have access to unlimited co2, therefore high levels of co2 will not upset your plants.
 

SRP3006

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Just whack up the co2, they will shed some emersed leaves. I'd be doing daily very large water changes though.
 
Last edited:

Zeus.

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Getting a pH drop of 1.0pH which will be about 30ppm would be helpful, but getting a stable pH four the first 4-5 hours of photo period is more important, even if you only manage to get a 0.5pH drop. It's stability and good flow in the tank are more important than the pH drop itself.
The plants will be use to getting 400ppm CO2 so will adjusting which normally takes about a week 'if' the CO2 is stable and the same for the first 4-5hrs from lights on.
If the CO2 is unstable your plants would be better off without CO2 injection IMO
 

ForestDave

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Getting a pH drop of 1.0pH which will be about 30ppm would be helpful, but getting a stable pH four the first 4-5 hours of photo period is more important, even if you only manage to get a 0.5pH drop. It's stability and good flow in the tank are more important than the pH drop itself.
The plants will be use to getting 400ppm CO2 so will adjusting which normally takes about a week 'if' the CO2 is stable and the same for the first 4-5hrs from lights on.
If the CO2 is unstable your plants would be better off without CO2 injection IMO
Cheers Zeus.
Yeah, the pH has been a bit variable as the needle valve is pretty much off or full soda stream, so even with the most minute of turns it's hard to change the setting by small amounts. My new regulator is in the post so that should be sorted soon. Thanks for the tip.
I'm hoping to decide on a hardscape in the next few days and get it all set up and planted so I'll work on a stable pH then. I cannot believe how difficult I've found choosing a hardscape layout!!
BTW on a separate note, do you lose many shrimp up the filter intake on the FX6 or have you shrimp proofed it in some way? I made a different attachment and covered it with a foam sleeve but am worried the flow is reduced too much, and also you lose the benefit of being able to suck out large particles of matter.
 

Zeus.

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I cannot believe how difficult I've found choosing a hardscape layout!!

I found it very time consuming and took many different 'mock-ups' to to happy with it.
do you lose many shrimp up the filter intake on the FX6 or have you shrimp proofed it in some way?

I did a stainless steel mesh insert for the FX6 filter intake, it reduces the number of RCS that get into the filter, just checked and dont have a pic off it will take one on next WC, some still get through, so when I do a filter clean I harvest the RCS from the filter sponges, I don't think the RCS have any issues being in the filter.
 

ForestDave

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I found it very time consuming and took many different 'mock-ups' to to happy with it.


I did a stainless steel mesh insert for the FX6 filter intake, it reduces the number of RCS that get into the filter, just checked and dont have a pic off it will take one on next WC, some still get through, so when I do a filter clean I harvest the RCS from the filter sponges, I don't think the RCS have any issues being in the filter.
Thanks for the reply. Yours and everyones help on this forum is so appreciated!

I've heard various horror stories from various people about tanks being overrun with algae and dying plants, I'm frantically trying to cover all my bases and not mess up.
Cheers!
 

Zeus.

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heard various horror stories from various people about tanks being overrun with algae and dying plants,

So prudent planning :thumbup:

I've heard various horror stories from various people about tanks being overrun with algae and dying plants

Unstable CO2 is the major cause of these outbreaks, so the outbreaks are mainly limited to tanks with CO2 injection or tanks with too much light/intensity. eg a low tach tank which may get direct sunlight seasonally when sun in low in the sky. If tank is low tech everything is slower so outbreaks happen slower and easier to manage/control. Flow in low tech tanks is much less critical. As @ceg4048 often says Flow is KING of the high tech tank, flow is still important in low tech but a lot less critical.
 

ForestDave

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Ah thanks mate. I appreciate the advice!!
I’ve opted for the FX6 with full width spray bar to hopefully take the easy route to good flow. My main concern is that it churns the floating plants around. I’ve stuck them in an old orange net bag to keep them under control. Not a stylish look though! I have been experimenting with pumping the filter water into both sides of the spray bar but I don’t think that doesn’t achieve anything extra and the floating plants just spin around annoyingly on both sides of the tank. Either way I can’t win. I may have to pipe from left to right with a narrower spray bar but it would foil my easy flow (Ceg style setup).
Any suggestions welcome again. 😂
 

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