Poor Plant Growth And Alge

[Ob1]

I have been having a number of problems with plant growth. I get great lush growth near the sub straight – the leaves looks great however they are small and tightly packed. After they reach 4 to 5 inches, all hell breaks lose – algae (hair both light green and very dark and blue green) cover the leaves completely – then the plants dies– I only plant fast growing plants.

I have noted that the plants have very thin stems that break very easy. And the leaves never grow long.

I have pressurised Co2, fairly good lighting (3.5watts / gallon) a wide light spectrum which includes 3 X T5 Plant Pros and 3 X D+D midday tubes (54watts each tube)

I have been trying to balance the tank without any luck – Has anyone had a similar problem?

My sub-straight is mainly fine gravel and includes a heating cable.

Water Reading
Phosphate 1mg/l
Nitrate 10-20mg/l
Iron .10mg/l

 

[George Farmer]

Interesting. At first glance you appear to have ideal conditions, this is of course if your test kit results are to be believed.

How are your NO3 and PO4 levels obtained? Via tap water and fish/food waste or dosing ferts too?

You run UV - why? This well render most micronutrients pretty useless quite quickly unless you are dosing very frequently. I personally believe that healthy, growing plants are the best water purifiers

You have ample light and CO2 (what is your CO2 level?) so the weak point is probably your macro/micronutrient levels. You aren't heavily stocked fish-wise so I assume that if you aren't dosing NO3 and PO4 seperately then your readings are wrong. Either that or you have insufficient plant bio-mass to utilise these nutrients produced via your fish.

I would recommend losing the UV and dosing more micronutrients. Possibly add some root tabs or similar to your substrate depending on species - Hygrophilas love a nutrient-rich substrate.

Keep an eye on NO3 and PO4 levels, when your plants grow better these levels will drop and you will need to consider dosing KNO3 and KH2PO4. Read zig's EI article for more.

One final thought is your lighting - how old are the tubes? I doubt this is the main cause but shifts in spectrums can influence algae growth.

Keep us updated.

 

[Ob1]

Hi gf225

I know what you mean about test kits they can be a real pain. I actually obtained some kno3 nitrate (UK) after I started to see zero nitrates reading on my tank last year- the idea was that nitrate is needed for plant growth. I never used any in the end, as after testing my tap water I found that too read zero.

Regarding my current kits I am sure both kits are OK. As I have seen the levels raise and fall across tap water / tanks water. Tap water comes in at 20mg/l and phosphates are around 2.5 to 5mg/l.

Current parameters

I have just added phosphate remover which has brought the phosphate down to 1mg/l - before that the phosphate were around 2.5.

NO3 reading have been very consistent at 20mg/l however the last reading it dropped to 10mg/l

I carry out 26gallon water changes every week, and have been adding Iron for the last 4 weeks to raise the iron levels to 0.10mg/l

No other frets added.

PH Around 7.00 - I have low KH 3 and GH slighty higher. I recall this means my co2 is at 8-10mg/l?


UV filter – very interesting comments – I have been using the UV over the last 18months and I must admit you may have a point the two do in some way co – inside with me seeing poor plant growth. I need more information about how the UV is affecting normal tap water micronutrients do you have any links / further info.


Substrate

When I set up the tank 3 years ago I did add a thin layer of laterite. This year mixed in some red fluorite.

Tubes

I had 6 plant pro installed for just under a year now. I noted that they had a very high spectrum around blue – I understand that this can course plants to grow stunted with short growth – Two weeks ago I replaced 3 plant pros with D+D midday's – which have a high red spectrum – which should provide some balance.


I had to carry out a major clean of the tank due to loads of hair algae – not the usual fine green but very dark green strings looks like wire – I think this may be too much iron?

appreciate your thoughts

 

[@ombomb]

It sounds similar to the algae I battled with, here's what mine looked like:

I'm pretty sure it's the same stuff especially as you have been seeing high phosphates in your tap water and have low CO² levels.

Keep is up with the phosphate removal, manually remove the algae, trim of the particularly covered leaves and increase your CO² levels to 35-40ppm until your tank is clean. Worked for me and I've been free of algae since. Once that's beaten you should be aiming for around 30ppm CO² and with a low KH, you will probably mean you have to add a buffer to your tank water.

 

[Jen]

Sounds like you need to up your CO2 levels. Most of us here in the planted section try to aim for 30mg/l.

 

[George Farmer]

As suggested you need more CO2 - 25 to 35ppm is ideal. Don't worry about your KH, 3 degrees is plenty. Aim for a pH of 6.5.

I would take out your phosphate remover. My tap water is 5ppm PO4 (2.5ppm with my 50:50 RO/tap water changes) and I still need to dose KH2PO4. As you have plenty of fast growers these will demand the extra PO4.

What iron fert are you using? You need to be dosing other micros too, especially as your tap water is soft and therefore probably lacking in nutrients.

Your recent change in lighting may have also contributed to your algae. Plants take time to adjust to new spectrums and the consequent temporary period in slowed growth will have helped the algae.