High pH, low KH, unwell plants

The Great Rumbini

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Apologies if this is not the correct forum section to ask advice or if this topic has been covered to death in other threads but I am new to this forum and a novice with aquariums in general.

I have a planted 20 gallon aquarium with fish and shrimp. The aquarium substrate I used was Carib Sea Eco Complete Planted Black Aquarium. The aquarium has been established for about 6-7 months. The water I use has a high pH: 8.2.

Following planting, the plants in the aquarium started off ok but haven't exactly thrived. Certain plant types such as crypts and Anubias are doing ok, whereas swords have very quite wan, yellowish leaves and do not grow much. Yet others such as Hygrophila, Ludwigia and Lobelia show slow growth, rapidly lose lower leaves and do not develop roots.

At first I thought the plant health issue might be to do with the high pH and that in hard water areas carbon is sequestered away and not readily available for aquatic plants. However, after using a KH test kit I found that the KH is actually very low (< 50 ppm), making this scenario unlikely.

Right now I am stumped as what is going wrong. Does anyone have any advice as to what could be causing the ill health in my plants and what steps I could take to improve it? I would prefer low maintenance options if possible but will take any advice I can get.

Thanks!
 

Zeus.

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Having a high pH and low kH doesn't make sense IMO. Test kits are not a reliable way to test your water parameters
Look up your water parameters for your location online.
Reading between the lines sounds initially there may be issues with ferts/flow/CO2.
Like Ed surgests a Pic and full tank details will help eg filter, lights, fert regime , CO2 etc
 

The Great Rumbini

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Hi and thanks for the replies,

Yes, I live in Hawaii, so mostly volcanic basaltic rock.

The tank is 20 gallons "long". I have an AquaClear 30 filter, with an additional Mylivell air pump. My light cycle is 8 hours 9-5 using a Beamswork DA 6500K 0.5W LED lighting system. Temperature ranges from 24 to 28C seasonally with no additional heating.

I don't generally add fertiliser because I (naively) thought the substrate and animals would provide what was needed, at least in the short term. I have tried adding Seachem Flourish a couple of times but it didn't seem to remedy things. I also have a bit of problem with algae so didn't really want to cause that to explode.

I have attached a recent photo of the aquarium. Hopefully it is of good enough quality.

Cheers,

Alan
 

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The Great Rumbini

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Having read around little more, I will try adding some bioaccessible carbon - this seems likely be the limiting factor. I have bought some Seachem Flourish Excel and will try this, alongside the Flourish micronutrients, and see if the plants pick up.

I will post a photo of the results (good or bad)
 

sparkyweasel

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Ferts are your limiting factor, Flourish is only trace elements.
Swords, Hygrophila, and Ludwigia will be fine with the CO2 the atmosphere provides, but will show the symptoms you describe if starved of nutrients. Eg, pale, yellow leaves. Swords a likely to show it first and more, as they are heavy feeders.
Excel, and other 'liquid CO2' products, divide opinions quite strongly, you might want to check out some threads on that before you decide. Even if it is any good, it won't provde the NPK your plants need.
 

The Great Rumbini

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Ferts are your limiting factor, Flourish is only trace elements.
Swords, Hygrophila, and Ludwigia will be fine with the CO2 the atmosphere provides, but will show the symptoms you describe if starved of nutrients. Eg, pale, yellow leaves. Swords a likely to show it first and more, as they are heavy feeders.
Excel, and other 'liquid CO2' products, divide opinions quite strongly, you might want to check out some threads on that before you decide. Even if it is any good, it won't provde the NPK your plants need.
I can't imagine it's the N levels given the animal life present in the tank. However, it could be low P & K. I will try supplementing these as well. Would you recommend Seachem Flourish Macronutrients as a good fertiliser brand?
 

The Great Rumbini

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Just in case anyone is interested, here is an up to date photo of my aquarium.

I now add K, P and micronutrients from the Flourish range a few times a week. I also add the recommended amount of Flourish Excel Bioavailable carbon daily, with no obvious detrimental affect on my shrimp, fish and (sadly) snails. I also, within the last couple of weeks, used NA thrive caps to fertilise the substrate, which seems to have given plant growth a huge boost.

Any comparison between the this photo and the older photo is slightly misleading as I have replaced dead plants and trimmed back moribund leaves. However, plant health is generally much better and algae growth much reduced. One thing I have noticed is that if I leave off supplementing nutrients for only couple of days, algal growth increases and plant leaves seem to decline in quality.

Thanks for all the advice!
 

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