Help! Problem with growing hairgrass

[CP]

Hi all, I have some problem with my hairgrass. The info of my tank is below.

Tank setup
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Age of tank : About 1 month
Dimesions of tank (LxWxH) : 4X1.5X1.5
Volume of water : about 200 litres (~ 53 US gallon)
Type of Filter (overhead/internal/canister) : Ehiem 2028 (Prof II)

Type of lighting (FL/PL/MH) : FL 6x32watt
Lighting Intensity : 3.6W/gallon
No. of hours of lighting : 8.5 hours

Type of CO2 (DIY/Liquid/Tank) : Tank
CO2 injection rate (bps): 2 bps

Substrate used : Dennerle crystal quartz/JBJ
Thickness of base fert : 1cm (2 tub of deponit mix-120)
Thickness of gravel : 5-15cm (sloping effect)

Type of liquid fertilizers used:
brand name: OTOTTO
Aqua-plant Nutrition and Aqua-plant Iron Plus
Other types of fertilizer used :
Root monster/laterite (mixed into substrate)
Frequency of fertilization : daily at half dosage

Temperature of tank : 27-28 deg

Other equipment : External reactor


Chemical Properties
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Carbonate Hardness (KH): 3.5
Total Hardness (gH): 4
pH : 6.7-7.0
NH4 (ppm): not measured
NO2 (ppm): not measured
NO3 (ppm): 5-10ppm
PO4 (ppm): not measured
Fe (ppm): not measured



Bioload
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Flora in tank :mainly hairgrass

Fauna in tank :
30 raspora espei
6 medium-sized cories
5 otos
30-50 cherry and green shrimp
6 horn snails


Description of problem(s):
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Hairgrass not growing well. The hairgrass are beginning to spread about 2 weeks ago after I gave them a trim to remove the immerse leave. However the hairgrass seems to spread very slowly and the new leave blades only reached about 3-4cm instead of the usual 6-7cm. Furthermore, I can see short strands of algae (possibly thread algae) growing on the leave. I do not think what I have is dwarf hairgrass. I do believe that what I see is stunt growth of normal hairgrass. Apart from hairgrass, there is a small plot of APP which is doing great, spreading and bubbling. Here are a few questions:

(1) Do I have enough CO2? Based on my KH (3.5DH) and pH 6.8 values (~3hr after turning on CO2), there should be about ~17ppm. I know this is not within the 20-30ppm target, but the bubble count is already 2bps. Should I increase the CO2?

(2) Should I increase the lighting duration? Intensity wise (3.6W/gallon) I think there should be enough but is 8 and a half hours enough?

(3) Is my substrate too deep? I have 2 tubs of deponit mix-120 mixed with laterite as my base fertilizer and then covered with a mixture of Dennerle crystal quartz and JBJ substrate such that it is sloping from the front (~5cm) to the back (~15cm). Is there a possibility that the fertilizer is too deep down for the root to reach? However, I do not see much different in growth between the front of the tank and the back.

(4) Is my liquid fertilizer dosage regime alright? I am using Aqua-plant Nutrition and Aqua-plant Iron Plus (brand OTOTTO) that I bought from Mermaid World. I am dosing both on a daily basis at half dosage strength. I am also dosing potassium sulphate on a daily basis (~2ppm K daily). Should I increase the dosage to full strength or change to weekly dosage? Please comment if you are using the same brand of liquid fertilizer. Should I stick to more reliable brand like Dennerle? Has anyone gotten good results growing hairgrass with any other less expansive brand of fertilizer?

(5) Is the temperature of 27-28°C alright? The chiller is set at 27°C and will turn on at 28°C.

(6) Should I trim the hairgrass again since they are covered with algae? How often should I trim them?

Thanks for helping
Regards
CP

[juggler]

Sorry I can't comment much as I don't use the same brand of fertiliser. Does it contain macro-nutrients like N,P and K?

Hairgrass grows slower than APP. So maybe give it more time to grow and cover the foreground. Maybe also increase the CO2 to rid the algae growing on the hairgrass.

You are already dosing for K using K2SO4. Want to switch to KNO3 so it can provide for N too? How about some KH2PO4 for the P?

[CP]

Hi Juggler, thanks for the advice. Aqua-plant Nutrition should contain the macro-nutrient and Aqua-plant Iron Plus containing Iron and micros according to what it says on the bottles.

As to the CO2 issue, I will try to increase it further…maybe up to 2.5bps….and then check on the pH. Hopefully the shrimps in my tank can take the change well.

As for dosing N and P, I am not so sure because my NO3 value will normally rise to the 20ppm range at the end of the week before water change….and not knowing the level of PO4 in my tank, I am hesitant to add any PO4.

Any other comments on my set up?

CP

[juggler]

Actually you can try PO4 dosing. I read that the PO4 from fish food is organic PO4 and plants prefer inorganic PO4. Our test kits measure both types of PO4.

Why not try 1ppm per week and see if there's any adverse effect? I dose 1.5 to 2ppm per week.